[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:19.58,Default,,0000,0000,0000,,{\i1}36c3 preroll music{\i0}
Dialogue: 0,0:00:19.58,0:00:23.10,Default,,0000,0000,0000,,Herald: So who is excited about\Nphotography or videography?
Dialogue: 0,0:00:23.10,0:00:28.32,Default,,0000,0000,0000,,{\i1}applaus{\i0}\NHerald: Yeah? The title of the talk kind
Dialogue: 0,0:00:28.32,0:00:35.79,Default,,0000,0000,0000,,of gives us gives it away. OK. We bet we\Nare waiting for the last people to come in
Dialogue: 0,0:00:35.79,0:00:44.16,Default,,0000,0000,0000,,and take a seat. Last time, raise your\Nhands if you have a free seat next to you.
Dialogue: 0,0:00:44.16,0:00:55.29,Default,,0000,0000,0000,,Every one of you coming in, look for raised hands\Nand take your seat and then we will start.
Dialogue: 0,0:00:55.29,0:01:19.39,Default,,0000,0000,0000,,Yeah, very good. OK. Looks like the doors\Nare finally closed. Okay, so the next talk
Dialogue: 0,0:01:19.39,0:01:26.90,Default,,0000,0000,0000,,on the second day is about ultrafast\Nimaging. So many of you have done
Dialogue: 0,0:01:26.90,0:01:34.15,Default,,0000,0000,0000,,videography or photography. Have thought\Nabout exposure time, how fast you can do
Dialogue: 0,0:01:34.15,0:01:39.87,Default,,0000,0000,0000,,your photography. And some of your might\Nhave played with lasers and have built
Dialogue: 0,0:01:39.87,0:01:45.54,Default,,0000,0000,0000,,blinky stuff with it or have done\Nscientific experiments and Caroline Will
Dialogue: 0,0:01:45.54,0:01:51.14,Default,,0000,0000,0000,,now show us what happens if we take those\Nto combine them and take it to the
Dialogue: 0,0:01:51.14,0:01:58.85,Default,,0000,0000,0000,,extreme. Caroline is working at DESY since\Nfour years. She has not done her PhD and
Dialogue: 0,0:01:58.85,0:02:05.62,Default,,0000,0000,0000,,is now working in a group for theoretical\Nfast modeling of inner workings of
Dialogue: 0,0:02:05.62,0:02:11.28,Default,,0000,0000,0000,,molecules and atoms. She is doing a\Ncomputational work and working together
Dialogue: 0,0:02:11.28,0:02:16.71,Default,,0000,0000,0000,,with experimentalists to verify their\Nobservations, and now she is presenting
Dialogue: 0,0:02:16.71,0:02:22.31,Default,,0000,0000,0000,,the inner mechanics of what she is doing\Nand how we can actually maybe photograph
Dialogue: 0,0:02:22.31,0:02:27.72,Default,,0000,0000,0000,,molecules by their forming. Applause!
Dialogue: 0,0:02:27.72,0:02:31.16,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:02:31.16,0:02:35.19,Default,,0000,0000,0000,,Caroline: Great. Yeah. Thank you very much\Nfor the introduction and thank you very
Dialogue: 0,0:02:35.19,0:02:40.17,Default,,0000,0000,0000,,much for having me here. I'm excited to\Nsee this room so full. So I'm going to
Dialogue: 0,0:02:40.17,0:02:44.68,Default,,0000,0000,0000,,speak today about an ultrashort history of\Nultrafast imaging. It's a really broad
Dialogue: 0,0:02:44.68,0:02:48.47,Default,,0000,0000,0000,,topic. And I'm just gonna present some\Nhighlights, some background. Before I
Dialogue: 0,0:02:48.47,0:02:53.86,Default,,0000,0000,0000,,start, I'd like to give you a few more few\Nmore words about myself. As we've already
Dialogue: 0,0:02:53.86,0:02:57.62,Default,,0000,0000,0000,,heard, I work at DESY, this is the DESY\Ncampus you see here and in the Center for
Dialogue: 0,0:02:57.62,0:03:03.28,Default,,0000,0000,0000,,Free Electron Laser Science, circle in\Norange. That's where I did my PhD. So this
Dialogue: 0,0:03:03.28,0:03:08.53,Default,,0000,0000,0000,,whole campus is located in Hamburg. This\Nis probably also a familiar place to many
Dialogue: 0,0:03:08.53,0:03:15.26,Default,,0000,0000,0000,,of you. And now this year we are in\NLeipzig a bit further away for the 36th
Dialogue: 0,0:03:15.26,0:03:21.30,Default,,0000,0000,0000,,Congress. So I'd like to start with a very\Nbroad question. What is the goal of
Dialogue: 0,0:03:21.30,0:03:25.52,Default,,0000,0000,0000,,ultrafast imaging? And we've heard already\Nthat ultrafast imaging is related to
Dialogue: 0,0:03:25.52,0:03:31.55,Default,,0000,0000,0000,,photography. Now, as many of you know,\Nwhen you take a picture, with a quite long
Dialogue: 0,0:03:31.55,0:03:36.39,Default,,0000,0000,0000,,exposure time, you see just a blurry\Nimage, for example, in this picture of a
Dialogue: 0,0:03:36.39,0:03:42.51,Default,,0000,0000,0000,,bowl of water. We can hardly see anything.\NIt looks a bit foggy. But if we choose the
Dialogue: 0,0:03:42.51,0:03:47.02,Default,,0000,0000,0000,,correct exposure time, which in this case\Nis 100 times shorter in the right picture
Dialogue: 0,0:03:47.02,0:03:51.25,Default,,0000,0000,0000,,than in the left picture, then we see a\Nclear image and we can see dynamics
Dialogue: 0,0:03:51.25,0:03:55.96,Default,,0000,0000,0000,,unfold. So we have here, a drop of water\Nthat is bouncing back from the bowl and
Dialogue: 0,0:03:55.96,0:04:00.47,Default,,0000,0000,0000,,also some ripples that are forming on the\Nsurface of this bowl. This is only visible
Dialogue: 0,0:04:00.47,0:04:06.33,Default,,0000,0000,0000,,because we chose the right exposure time.\NAnd this is to me really the key of being
Dialogue: 0,0:04:06.33,0:04:13.23,Default,,0000,0000,0000,,successful in ultrafast imaging to take a\Nclear picture of an object that is moving.
Dialogue: 0,0:04:13.23,0:04:17.13,Default,,0000,0000,0000,,But it's not enough to say take just a\Npicture. So now imagine you're a sports
Dialogue: 0,0:04:17.13,0:04:20.68,Default,,0000,0000,0000,,reporter. You get these two pictures and\Nyou're supposed to write up what happened.
Dialogue: 0,0:04:20.68,0:04:25.66,Default,,0000,0000,0000,,So it's complicated. So the top picture is\Nthe start, the bottom pictures is the end.
Dialogue: 0,0:04:25.66,0:04:30.50,Default,,0000,0000,0000,,Just from these two pictures, it's hard to\Nsee. But if we see before picture, we can
Dialogue: 0,0:04:30.50,0:04:35.17,Default,,0000,0000,0000,,see very complex dynamics unfold. There\Nare particles accelerating at high
Dialogue: 0,0:04:35.17,0:04:41.09,Default,,0000,0000,0000,,velocity {\i1}laughing{\i0} coming in from the back. And even\Nparticles we did not see in the first
Dialogue: 0,0:04:41.09,0:04:46.33,Default,,0000,0000,0000,,picture at all somehow are very relevant\Nto our motion. And not only skiing races
Dialogue: 0,0:04:46.33,0:04:52.27,Default,,0000,0000,0000,,are very dynamic, but most processes in\Nnature are also not static. This is true
Dialogue: 0,0:04:52.27,0:04:55.89,Default,,0000,0000,0000,,for everything we see around ourselves,\Nbut it's especially true for everything
Dialogue: 0,0:04:55.89,0:05:01.37,Default,,0000,0000,0000,,that is quite small in the microcosm. And\Nin general, we can gain a lot more insight
Dialogue: 0,0:05:01.37,0:05:08.36,Default,,0000,0000,0000,,from time resolved images. So from ultra\Nshort movies. I'd like to show you the
Dialogue: 0,0:05:08.36,0:05:12.27,Default,,0000,0000,0000,,very first ultrafast movie that was ever\Ntaken. Or maybe even the first movie that
Dialogue: 0,0:05:12.27,0:05:19.96,Default,,0000,0000,0000,,was taken at all. This guy, Eadweard\NMuybridge lived in the 19th century. And
Dialogue: 0,0:05:19.96,0:05:24.77,Default,,0000,0000,0000,,very shortly after the invention of a\Nphotography method, he tried to answer the
Dialogue: 0,0:05:24.77,0:05:29.90,Default,,0000,0000,0000,,question does a galloping horse ever lift\Nall of its feet off the ground? Why, it's
Dialogue: 0,0:05:29.90,0:05:34.46,Default,,0000,0000,0000,,running. To us, it may seem like not so\Nimportant question, but in the 19th
Dialogue: 0,0:05:34.46,0:05:39.56,Default,,0000,0000,0000,,century, the horse was the main method of\Ntransportation, and horse races were very
Dialogue: 0,0:05:39.56,0:05:45.49,Default,,0000,0000,0000,,popular. So there was a lot of interest in\Nstudying the dynamics of a horse, and this
Dialogue: 0,0:05:45.49,0:05:50.26,Default,,0000,0000,0000,,process is too fast to see with the naked\Neye. But Muybridge implemented a stop
Dialogue: 0,0:05:50.26,0:05:55.04,Default,,0000,0000,0000,,motion technique where the horse as it is\Nrunning, cuts some wires, that then
Dialogue: 0,0:05:55.04,0:06:00.13,Default,,0000,0000,0000,,trigger photographs. And with this he was\Nable to take these twelve photographs of
Dialogue: 0,0:06:00.13,0:06:05.22,Default,,0000,0000,0000,,the horse in motion. That was published\Nunder this title in Stanford in the 19th
Dialogue: 0,0:06:05.22,0:06:10.08,Default,,0000,0000,0000,,century. And we see very clearly in the\Ntop row third picture and maybe also
Dialogue: 0,0:06:10.08,0:06:14.33,Default,,0000,0000,0000,,second picture that indeed the horse lifts\Nall of its legs off the ground, which was
Dialogue: 0,0:06:14.33,0:06:20.17,Default,,0000,0000,0000,,a new insight at that time. And when we\Nstitch all of these snapshots together, we
Dialogue: 0,0:06:20.17,0:06:24.86,Default,,0000,0000,0000,,have an ultra fast movie of a horse\Ngalloping, which might be seen as the
Dialogue: 0,0:06:24.86,0:06:31.26,Default,,0000,0000,0000,,first movie that was ever made in the\Nhistory of mankind. Now, when I say
Dialogue: 0,0:06:31.26,0:06:35.55,Default,,0000,0000,0000,,ultrafast today, I'm no longer thinking\Nabout horses, but about smaller things and
Dialogue: 0,0:06:35.55,0:06:40.57,Default,,0000,0000,0000,,faster things. But let's go there, very\Ngently. So the time scale that we are all
Dialogue: 0,0:06:40.57,0:06:44.91,Default,,0000,0000,0000,,familiar with that we can see with the\Nnaked eye is something of the order of
Dialogue: 0,0:06:44.91,0:06:50.15,Default,,0000,0000,0000,,seconds. So, for example, the acceleration\Nof this cheetah, we can see with the naked
Dialogue: 0,0:06:50.15,0:06:56.35,Default,,0000,0000,0000,,eye. Now, if we zoom in on this motion, we\Nsee that there are muscles inside of the
Dialogue: 0,0:06:56.35,0:07:00.93,Default,,0000,0000,0000,,animal that are contracting as it is\Nrunning. And this muscle contraction takes
Dialogue: 0,0:07:00.93,0:07:06.81,Default,,0000,0000,0000,,place within milliseconds. So that's a\Npart of a thousand in one second. But we
Dialogue: 0,0:07:06.81,0:07:11.32,Default,,0000,0000,0000,,can go even smaller than that to the\Nmicrosecond. So proteins inside of the
Dialogue: 0,0:07:11.32,0:07:17.18,Default,,0000,0000,0000,,muscles or in any biologic matter fold and\Nunfold on a timescale of microseconds.
Dialogue: 0,0:07:17.18,0:07:22.51,Default,,0000,0000,0000,,That's already a part in a million of a\Nsecond. Now going even smaller, to
Dialogue: 0,0:07:22.51,0:07:29.08,Default,,0000,0000,0000,,nanoseconds there's certain dynamics that\Ntake place within these proteins, for
Dialogue: 0,0:07:29.08,0:07:34.09,Default,,0000,0000,0000,,example, of how they dissolve in water.\NBut the timescale that I'm interested in
Dialogue: 0,0:07:34.09,0:07:38.97,Default,,0000,0000,0000,,today is the femtosecond. It's even faster\Nthan that it's the timescale where
Dialogue: 0,0:07:38.97,0:07:44.54,Default,,0000,0000,0000,,individual atoms move in molecules as\Nshown in this animation. Now a
Dialogue: 0,0:07:44.54,0:07:49.20,Default,,0000,0000,0000,,femtosecond is very short. It's a part in\Na million of a billion of a second, or as
Dialogue: 0,0:07:49.20,0:07:55.04,Default,,0000,0000,0000,,we physicists like to call it, ten to the\Nminus 15 seconds because it's easier to
Dialogue: 0,0:07:55.04,0:08:01.69,Default,,0000,0000,0000,,spell {\i1}laughing{\i0} to us. We can - to us - , we can go even\Nfaster than that. The time scale of
Dialogue: 0,0:08:01.69,0:08:05.39,Default,,0000,0000,0000,,electronic motion and in molecules would\Nbe an attosecond. I'm just mentioning it
Dialogue: 0,0:08:05.39,0:08:12.34,Default,,0000,0000,0000,,here because we don't stop at molecules,\Nbut nature is even faster than that. But
Dialogue: 0,0:08:12.34,0:08:15.03,Default,,0000,0000,0000,,for the purpose of this talk, I will\Nmainly focus on processes that take place
Dialogue: 0,0:08:15.03,0:08:21.74,Default,,0000,0000,0000,,within the femtosecond. So within ten to\Nthe minus fifteen seconds. Now, this time
Dialogue: 0,0:08:21.74,0:08:26.41,Default,,0000,0000,0000,,scale is something that is not really\Nrelated to what we think about in everyday
Dialogue: 0,0:08:26.41,0:08:31.15,Default,,0000,0000,0000,,life. But there are certain processes in\Nchemistry, biology and physics that are
Dialogue: 0,0:08:31.15,0:08:36.42,Default,,0000,0000,0000,,really fundamental and that start at this\Ntime scale. Just to give you an idea how
Dialogue: 0,0:08:36.42,0:08:42.07,Default,,0000,0000,0000,,short a femtosecond is, the width of a\Nhuman hair is about 100 micrometer. It's
Dialogue: 0,0:08:42.07,0:08:47.13,Default,,0000,0000,0000,,shown here in an electron microscopic\Npicture. And for light at the speed of
Dialogue: 0,0:08:47.13,0:08:53.75,Default,,0000,0000,0000,,light, it takes only thirty femtoseconds\Nto cross the hair. So that's how fast a
Dialogue: 0,0:08:53.75,0:08:58.95,Default,,0000,0000,0000,,femtosecond is. And even although this\Ntimescale is so short, there are many
Dialogue: 0,0:08:58.95,0:09:03.73,Default,,0000,0000,0000,,important processes that start here, I'd\Nlike to mention, just two of them. The
Dialogue: 0,0:09:03.73,0:09:07.63,Default,,0000,0000,0000,,first one is vision in our eyes and our\Nretina there sits a molecule called
Dialogue: 0,0:09:07.63,0:09:13.66,Default,,0000,0000,0000,,rhodopsin, that is shown here to the left.\NAnd when light hits rhodopsin, it starts
Dialogue: 0,0:09:13.66,0:09:18.87,Default,,0000,0000,0000,,to isomorphise, which is a fancy word for\Nsaying it changes its shape. And this
Dialogue: 0,0:09:18.87,0:09:24.76,Default,,0000,0000,0000,,transmits, in the end, electrical impulses\Nto our brain, which enables us to see. And
Dialogue: 0,0:09:24.76,0:09:28.85,Default,,0000,0000,0000,,this very first step of vision takes only\Ntwo hundred femtoseconds to complete. But
Dialogue: 0,0:09:28.85,0:09:33.06,Default,,0000,0000,0000,,without it, vision would not be possible.\NAnother very fast process that is
Dialogue: 0,0:09:33.06,0:09:39.65,Default,,0000,0000,0000,,fundamental in nature is photosynthesis,\Nwhere plants take light and CO2 and
Dialogue: 0,0:09:39.65,0:09:45.74,Default,,0000,0000,0000,,convert it to other things, among them\Noxygen. And the very first excitation
Dialogue: 0,0:09:45.74,0:09:53.11,Default,,0000,0000,0000,,where light hits the plant and it starts\Nto make all this energy available. That
Dialogue: 0,0:09:53.11,0:09:56.69,Default,,0000,0000,0000,,also takes less than one hundredth\Nfemtoseconds to complete. So really the
Dialogue: 0,0:09:56.69,0:10:01.93,Default,,0000,0000,0000,,fundamental questions of life lie at this\Ntimescale. And I'd like to just mention
Dialogue: 0,0:10:01.93,0:10:06.82,Default,,0000,0000,0000,,that all of these processes are not only\Nvery fast, but they also take place in
Dialogue: 0,0:10:06.82,0:10:11.54,Default,,0000,0000,0000,,very small objects, that are of a size of\Na few atoms to nanometers, which makes it
Dialogue: 0,0:10:11.54,0:10:15.48,Default,,0000,0000,0000,,also hard to observe because we cannot see\Nthem with the naked eye or with standard
Dialogue: 0,0:10:15.48,0:10:22.24,Default,,0000,0000,0000,,microscopes. Now, we've seen already that\Nit's important to choose the right
Dialogue: 0,0:10:22.24,0:10:28.19,Default,,0000,0000,0000,,exposure time to get a clear image of\Nsomething that's moving, but the kind of
Dialogue: 0,0:10:28.19,0:10:32.51,Default,,0000,0000,0000,,method that we need for taking such a\Nphotograph of something that is moving
Dialogue: 0,0:10:32.51,0:10:37.22,Default,,0000,0000,0000,,depends a lot on the timescale. So for\Nstuff that is moving within seconds or
Dialogue: 0,0:10:37.22,0:10:43.46,Default,,0000,0000,0000,,fractions of a second, we can see that\Nwith the naked eye, we can use cameras to
Dialogue: 0,0:10:43.46,0:10:48.18,Default,,0000,0000,0000,,resolve faster motion, very much like\NMuybridge did with the very first camera.
Dialogue: 0,0:10:48.18,0:10:53.50,Default,,0000,0000,0000,,Today, of course, we can go much faster to\Nmaybe a few microseconds. With very fancy
Dialogue: 0,0:10:53.50,0:10:57.23,Default,,0000,0000,0000,,cameras called opto-electronic street\Ncameras - i won't go into detail here - we
Dialogue: 0,0:10:57.23,0:11:01.56,Default,,0000,0000,0000,,can go down to picoseconds. So we are\Nalready very close to the motion of
Dialogue: 0,0:11:01.56,0:11:06.90,Default,,0000,0000,0000,,molecules, but we are not quite there yet.\NThe timescale that we want to investigate
Dialogue: 0,0:11:06.90,0:11:11.06,Default,,0000,0000,0000,,is a femtosecond. So really a time\Ntimescale of molecular motion and
Dialogue: 0,0:11:11.06,0:11:16.55,Default,,0000,0000,0000,,electronics are not fast enough to reach\Nthis timescale. So we need something new.
Dialogue: 0,0:11:16.55,0:11:21.38,Default,,0000,0000,0000,,And fortunately, we can create light\Npulses that serve as to say flashes, but
Dialogue: 0,0:11:21.38,0:11:26.20,Default,,0000,0000,0000,,take snapshots of our moving molecules\Nwith femtosecond time resolution and light
Dialogue: 0,0:11:26.20,0:11:31.97,Default,,0000,0000,0000,,pulses can be made so short. So in the\Nfollowing, I'm going to show you a bit
Dialogue: 0,0:11:31.97,0:11:37.55,Default,,0000,0000,0000,,more detail on how we can use these ultra\Nshort light pulses to take snapshots of
Dialogue: 0,0:11:37.55,0:11:43.70,Default,,0000,0000,0000,,moving molecules. The first method that I\Nwould like to briefly show you is X-Ray
Dialogue: 0,0:11:43.70,0:11:49.12,Default,,0000,0000,0000,,diffraction, where we have an ultra short\Npulse, an X-Ray pulse coming in. It hits a
Dialogue: 0,0:11:49.12,0:11:54.90,Default,,0000,0000,0000,,sample shown here in the red bubbles.\NThat's essentially a molecule that that we
Dialogue: 0,0:11:54.90,0:12:01.54,Default,,0000,0000,0000,,just place in the beam and it produces a\Nso-called diffraction pattern that we can
Dialogue: 0,0:12:01.54,0:12:07.83,Default,,0000,0000,0000,,then record on a screen. Now, the whole\Nprocess is quite complicated. So I like to
Dialogue: 0,0:12:07.83,0:12:15.42,Default,,0000,0000,0000,,just sketch the very basics of it. We see\Nhere X-Ray radiation hitting a crystalline
Dialogue: 0,0:12:15.42,0:12:23.04,Default,,0000,0000,0000,,sample here to the left and the sample is\Nexcited, starts to radiate X-Ray back and
Dialogue: 0,0:12:23.04,0:12:29.20,Default,,0000,0000,0000,,on the right we can see the X-Rays leaving\Nthe sample again. They will interfere and
Dialogue: 0,0:12:29.20,0:12:34.67,Default,,0000,0000,0000,,we can record this pattern on the screen.\NSo this is what we see here in this
Dialogue: 0,0:12:34.67,0:12:42.57,Default,,0000,0000,0000,,visualization to the right. With this, we\Ncan feed a reconstructionalgorithm that
Dialogue: 0,0:12:42.57,0:12:47.11,Default,,0000,0000,0000,,allows us to transform back our\Ndiffraction pattern that we've seen here
Dialogue: 0,0:12:47.11,0:12:53.57,Default,,0000,0000,0000,,for for in this case a bio molecule. We\Ncan reconstruct from that the image as it
Dialogue: 0,0:12:53.57,0:13:00.90,Default,,0000,0000,0000,,was in real space. So this is some\Nprotein, I believe. X-ray diffraction is
Dialogue: 0,0:13:00.90,0:13:09.15,Default,,0000,0000,0000,,very nice for resolving small structures\Nwith atomic detail. Another method how we
Dialogue: 0,0:13:09.15,0:13:15.56,Default,,0000,0000,0000,,can take snapshots using ultra short\Npulses, that I would like to briefly
Dialogue: 0,0:13:15.56,0:13:20.83,Default,,0000,0000,0000,,introduce is absorption spectroscopy. Now\Nyou may know that light contains several
Dialogue: 0,0:13:20.83,0:13:27.54,Default,,0000,0000,0000,,colors. For example, you've surely have\Nheld a prism in hand, and the prism can
Dialogue: 0,0:13:27.54,0:13:32.13,Default,,0000,0000,0000,,break white light up into all the colors\Nof a rainbow, that we can see with the
Dialogue: 0,0:13:32.13,0:13:38.15,Default,,0000,0000,0000,,eye. Now we can do the same with X-Ray\Npulses. Then we cannot see the colors
Dialogue: 0,0:13:38.15,0:13:44.41,Default,,0000,0000,0000,,anymore. So just let's just stick with a\Nprism here. When we place a molecule in
Dialogue: 0,0:13:44.41,0:13:49.20,Default,,0000,0000,0000,,front of all these colors, the molecule\Nwill block certain colors. That's quantum
Dialogue: 0,0:13:49.20,0:13:56.92,Default,,0000,0000,0000,,mechanics. You just have to believe it or\Nlearn about it in long studies. So the
Dialogue: 0,0:13:56.92,0:14:03.11,Default,,0000,0000,0000,,molecule is placed in front of all these\Ncolors. And to be right, the absorption
Dialogue: 0,0:14:03.11,0:14:08.11,Default,,0000,0000,0000,,spectrum is recorded and the parts of the\Nspectrum that are very bright correspond
Dialogue: 0,0:14:08.11,0:14:14.48,Default,,0000,0000,0000,,to the colors that have been blocked by\Nthe molecule. And this is a very nice
Dialogue: 0,0:14:14.48,0:14:19.09,Default,,0000,0000,0000,,technique to investigate ultra short\Ndynamics, because where these lines are
Dialogue: 0,0:14:19.09,0:14:24.88,Default,,0000,0000,0000,,located is characteristic of the chemical\Nelements that we find in the molecule. For
Dialogue: 0,0:14:24.88,0:14:28.76,Default,,0000,0000,0000,,example, if we use X-Ray radiation for\Nthis specific molecule, that I've shown
Dialogue: 0,0:14:28.76,0:14:33.81,Default,,0000,0000,0000,,here lysine, that's not so important which\Nmolecule it is. We have three different
Dialogue: 0,0:14:33.81,0:14:39.27,Default,,0000,0000,0000,,atoms in this molecule that are important\Ncarbon, nitrogen and oxygen and they
Dialogue: 0,0:14:39.27,0:14:43.88,Default,,0000,0000,0000,,absorb at very different colors so we can\Nkeep them apart when we take the spectrum.
Dialogue: 0,0:14:43.88,0:14:49.12,Default,,0000,0000,0000,,But not only that, we can take the\Nspectrum at a later time when the molecule
Dialogue: 0,0:14:49.12,0:14:54.42,Default,,0000,0000,0000,,has moved around a bit and we will see\Nthat the colors, the position of the lines
Dialogue: 0,0:14:54.42,0:14:59.83,Default,,0000,0000,0000,,have changed a tiny bit. So it's really\Nnot much and I accelerated it already in
Dialogue: 0,0:14:59.83,0:15:06.07,Default,,0000,0000,0000,,this visualization quite a bit. But with\Nexperimental methods, we can resolve this.
Dialogue: 0,0:15:06.07,0:15:11.42,Default,,0000,0000,0000,,And this allows us to then trace back to\Nhow the molecule was moving in between
Dialogue: 0,0:15:11.42,0:15:16.89,Default,,0000,0000,0000,,when we took these two snapshots. There\Nare many more methods that you can use to
Dialogue: 0,0:15:16.89,0:15:21.82,Default,,0000,0000,0000,,take ultrafast images. So we call them\Nprobe signals because we probe the
Dialogue: 0,0:15:21.82,0:15:26.89,Default,,0000,0000,0000,,ultrafast motion of a molecule with such\Nan ultra short pulse. For example, we can
Dialogue: 0,0:15:26.89,0:15:33.01,Default,,0000,0000,0000,,record photo electrons or we can record\Nfragments of a molecule and many more. But
Dialogue: 0,0:15:33.01,0:15:37.52,Default,,0000,0000,0000,,I won't go into further detail here\Nbecause this is not an exhaustive list of
Dialogue: 0,0:15:37.52,0:15:42.32,Default,,0000,0000,0000,,methods that we can use. I'd rather like\Nto show you how we can take molecular
Dialogue: 0,0:15:42.32,0:15:47.71,Default,,0000,0000,0000,,movies so how we can combine all these\Nultrashort pulses to in the end film a
Dialogue: 0,0:15:47.71,0:15:55.05,Default,,0000,0000,0000,,molecule in action. Now we've already seen\Nin the movie of the horse that we need to
Dialogue: 0,0:15:55.05,0:16:00.99,Default,,0000,0000,0000,,stitch several snapshots together and then\Nwe have a full picture, full motion of a
Dialogue: 0,0:16:00.99,0:16:06.74,Default,,0000,0000,0000,,molecule. So we just like to do the same,\Nbut ten to the 15 times faster, should not
Dialogue: 0,0:16:06.74,0:16:13.03,Default,,0000,0000,0000,,be too difficult, right? So we use our\Nultra short pulse. First ultrasound parts
Dialogue: 0,0:16:13.03,0:16:17.98,Default,,0000,0000,0000,,that we use as a trigger, parts that sets\Noff the motion and the molecule. This
Dialogue: 0,0:16:17.98,0:16:22.41,Default,,0000,0000,0000,,defines us a certain time zero in our\Nexperiment and makes it sort of repeatable
Dialogue: 0,0:16:22.41,0:16:28.30,Default,,0000,0000,0000,,because we always start the same kind of\Nmotion by giving it a small hit and now
Dialogue: 0,0:16:28.30,0:16:34.87,Default,,0000,0000,0000,,it's just moving around. So we wait for a\Ncertain time, a time delay and then come
Dialogue: 0,0:16:34.87,0:16:40.94,Default,,0000,0000,0000,,in with a probe pulse. The probe pulse\Ntakes a snapshot of a molecule. This goes
Dialogue: 0,0:16:40.94,0:16:45.32,Default,,0000,0000,0000,,to some detector, goes to a kind of\Ncomplicated reconstruction method that we
Dialogue: 0,0:16:45.32,0:16:51.71,Default,,0000,0000,0000,,just execute from our screen. And with\Nthis, we reconstruct a snapshot of a
Dialogue: 0,0:16:51.71,0:16:56.85,Default,,0000,0000,0000,,molecule. But this is only one snapshot\Nand we want a whole movie. So we need to
Dialogue: 0,0:16:56.85,0:17:02.24,Default,,0000,0000,0000,,repeat this process over and over again by\Nshining and more and more probe pulses.
Dialogue: 0,0:17:02.24,0:17:08.04,Default,,0000,0000,0000,,And this will create more and more\Nsnapshots of a molecule. And in the end,
Dialogue: 0,0:17:08.04,0:17:12.21,Default,,0000,0000,0000,,we could stitch all of these together and\Nwe would arrive at the same image that you
Dialogue: 0,0:17:12.21,0:17:18.43,Default,,0000,0000,0000,,see in the in the middle where the\Nmolecules is happily moving around. There
Dialogue: 0,0:17:18.43,0:17:24.79,Default,,0000,0000,0000,,is one little problem: The probe pulse\Ntypically destroys the molecule. This is
Dialogue: 0,0:17:24.79,0:17:28.50,Default,,0000,0000,0000,,very different. This is very different\Nfrom taking pictures of a horse. The horse
Dialogue: 0,0:17:28.50,0:17:36.29,Default,,0000,0000,0000,,normally survives. {\i1}laughting{\i0} So the probe pulse\Ndestroys the molecule. It just goes away.
Dialogue: 0,0:17:36.29,0:17:41.83,Default,,0000,0000,0000,,So for each of these snapshots we need to\Nuse a new molecule. So we typically have a
Dialogue: 0,0:17:41.83,0:17:47.97,Default,,0000,0000,0000,,stream of samples that is falling from the\Ntop to the bottom in our experiment. And
Dialogue: 0,0:17:47.97,0:17:51.69,Default,,0000,0000,0000,,then we have to carefully align two pulses\Na trigger pulse and a probe pulse that
Dialogue: 0,0:17:51.69,0:17:57.61,Default,,0000,0000,0000,,come together and take a snapshot of this\Nmolecule. And of course, we have to find a
Dialogue: 0,0:17:57.61,0:18:03.12,Default,,0000,0000,0000,,method on how to make identical molecules\Navailable in - Yeah - you see, there's a
Dialogue: 0,0:18:03.12,0:18:07.86,Default,,0000,0000,0000,,lot of complications with doing these\Nexperiments that I'm completely leaving
Dialogue: 0,0:18:07.86,0:18:15.09,Default,,0000,0000,0000,,out here. So now we want to take a\Nmolecular movie and we know that we want
Dialogue: 0,0:18:15.09,0:18:19.70,Default,,0000,0000,0000,,to have ultra short pulses to do so. But I\Ndidn't tell you yet what kind of light
Dialogue: 0,0:18:19.70,0:18:24.75,Default,,0000,0000,0000,,source we need. So there are many light\Nsources all around us. We have here lights
Dialogue: 0,0:18:24.75,0:18:29.45,Default,,0000,0000,0000,,from lamps. I have a light in my laser\Npointer with light from the sun. But we
Dialogue: 0,0:18:29.45,0:18:35.38,Default,,0000,0000,0000,,need quite specific light sources to take\Nthese snapshots of molecular motion. We've
Dialogue: 0,0:18:35.38,0:18:37.97,Default,,0000,0000,0000,,already established that we want\Nultrashort pulses because else we cannot
Dialogue: 0,0:18:37.97,0:18:44.26,Default,,0000,0000,0000,,resolve femtosecond dynamics, but for the\Nproper kind of wavelength that we need I
Dialogue: 0,0:18:44.26,0:18:47.98,Default,,0000,0000,0000,,would like to quickly remind you of the\Nelectromagnetic spectrum that you've
Dialogue: 0,0:18:47.98,0:18:54.09,Default,,0000,0000,0000,,probably seen at some point in high\Nschool. So, so light, as you see here in
Dialogue: 0,0:18:54.09,0:18:58.97,Default,,0000,0000,0000,,the bottom picture is an electromagnetic\Nwave that comes in different wavelengths.
Dialogue: 0,0:18:58.97,0:19:05.44,Default,,0000,0000,0000,,They can be quite long as in the case of\Nradio waves to the very left. Then we have
Dialogue: 0,0:19:05.44,0:19:08.47,Default,,0000,0000,0000,,the region of visible light shown here as\Nthe rainbow that we can perceive with our
Dialogue: 0,0:19:08.47,0:19:14.27,Default,,0000,0000,0000,,eyes. And then we have wavelengths that\Nare too short to see with our eyes. First,
Dialogue: 0,0:19:14.27,0:19:18.88,Default,,0000,0000,0000,,UV radiation, that gives us a tan in the\Nsummer if we leave our house and then we
Dialogue: 0,0:19:18.88,0:19:25.40,Default,,0000,0000,0000,,have X-ray radiation, soft and hard X-ray\Nradiation that have atomic wavelength. So
Dialogue: 0,0:19:25.40,0:19:30.57,Default,,0000,0000,0000,,the wavelength is really on the order of\Nthe size of an atom. So what kind of
Dialogue: 0,0:19:30.57,0:19:37.08,Default,,0000,0000,0000,,wavelength do we need to study ultra short\Ndynamics - ultra fast dynamics? We can
Dialogue: 0,0:19:37.08,0:19:43.32,Default,,0000,0000,0000,,first think about what kind of wavelength\Nwe need when we want to construct an ultra
Dialogue: 0,0:19:43.32,0:19:49.60,Default,,0000,0000,0000,,short pulse. I've drawn here two pulses to\Nthe left, a slightly longer pulse to the
Dialogue: 0,0:19:49.60,0:19:53.98,Default,,0000,0000,0000,,right, a shorter pulse. And now if you\Nthink about squeezing the left parts
Dialogue: 0,0:19:53.98,0:19:58.61,Default,,0000,0000,0000,,together such that it becomes shorter and\Nshorter, you see visually that the
Dialogue: 0,0:19:58.61,0:20:03.89,Default,,0000,0000,0000,,wavelength also needs to shrink. So we\Nneed shorter wavelengths for the shorter
Dialogue: 0,0:20:03.89,0:20:10.35,Default,,0000,0000,0000,,the pulse we want to make. So this will be\Nlocated somewhere here in this region of
Dialogue: 0,0:20:10.35,0:20:15.45,Default,,0000,0000,0000,,the electromagnetic spectrum. And another\Nimportant thing that we need to keep in
Dialogue: 0,0:20:15.45,0:20:21.25,Default,,0000,0000,0000,,mind is if we want to take pictures by\NX-ray diffraction, we are limited, so we
Dialogue: 0,0:20:21.25,0:20:27.43,Default,,0000,0000,0000,,can only resolve structures that are about\Nthe same size as the wavelength we used to
Dialogue: 0,0:20:27.43,0:20:31.92,Default,,0000,0000,0000,,take our diffraction image. So if we want\Nto take a picture of something with atomic
Dialogue: 0,0:20:31.92,0:20:37.55,Default,,0000,0000,0000,,resolution, our wavelength needs to be of\Natomic size as well. And this places us in
Dialogue: 0,0:20:37.55,0:20:47.17,Default,,0000,0000,0000,,the region of X-Rays drawn here, that have\Na wavelength of less than a nanometer. So
Dialogue: 0,0:20:47.17,0:20:51.51,Default,,0000,0000,0000,,we can establish that we want small\Nwavelengths in general. We have two
Dialogue: 0,0:20:51.51,0:20:55.84,Default,,0000,0000,0000,,additional requirements that would just\Ntouch upon very briefly. First, we need
Dialogue: 0,0:20:55.84,0:21:01.46,Default,,0000,0000,0000,,very brilliant pulses because the pulses\Nare so short, we need to have a lot of
Dialogue: 0,0:21:01.46,0:21:06.76,Default,,0000,0000,0000,,light in the short pulse. You can think\Nabout taking a picture in a dark room with
Dialogue: 0,0:21:06.76,0:21:12.27,Default,,0000,0000,0000,,a bad camera. You won't see anything. So\Nwe need very bright flashes of light.
Dialogue: 0,0:21:12.27,0:21:16.16,Default,,0000,0000,0000,,Another requirement is we need coherent\Nlaser light. So we cannot just use any
Dialogue: 0,0:21:16.16,0:21:20.13,Default,,0000,0000,0000,,light, but it needs to have certain\Nproperties like laser light.
Dialogue: 0,0:21:20.13,0:21:25.11,Default,,0000,0000,0000,,Unfortunately, the lasers that you can buy\Ncommercially do not operate in the region
Dialogue: 0,0:21:25.11,0:21:29.11,Default,,0000,0000,0000,,of the electromagnetic spectrum that we\Nare interested in. So we need to come up
Dialogue: 0,0:21:29.11,0:21:34.83,Default,,0000,0000,0000,,with something new. And I will show you\Nhow we can generate ultra short pulses
Dialogue: 0,0:21:34.83,0:21:39.38,Default,,0000,0000,0000,,both in the laboratory where we can\Ngenerate pulses that are very short and
Dialogue: 0,0:21:39.38,0:21:46.65,Default,,0000,0000,0000,,extend up to maybe the soft X-ray region.\NAnd another method to generate ultra short
Dialogue: 0,0:21:46.65,0:21:53.38,Default,,0000,0000,0000,,pulses is at free electron laser sources,\Nwhere we can go really to the hard X-Ray
Dialogue: 0,0:21:53.38,0:21:59.48,Default,,0000,0000,0000,,regime. But first I'd like to go to the\Nlaboratory. So in the laboratory, it's
Dialogue: 0,0:21:59.48,0:22:03.38,Default,,0000,0000,0000,,possible to generate an ultrashort pulse by\Nusing a process that's called high
Dialogue: 0,0:22:03.38,0:22:08.20,Default,,0000,0000,0000,,harmonic generation. In high harmonic\Ngeneration we start off of a high
Dialogue: 0,0:22:08.20,0:22:13.47,Default,,0000,0000,0000,,intensity pulse, that's a red pulse coming\Nin from the left, which which is focused
Dialogue: 0,0:22:13.47,0:22:19.35,Default,,0000,0000,0000,,in a gas cell. And from there, it\Ngenerates new frequencies of light. So the
Dialogue: 0,0:22:19.35,0:22:24.77,Default,,0000,0000,0000,,light that comes out is no longer red, but\Nit's violet, blue. We cannot see it with
Dialogue: 0,0:22:24.77,0:22:27.98,Default,,0000,0000,0000,,the naked eye. So that's an artist's\Nimpression of how high harmonic generation
Dialogue: 0,0:22:27.98,0:22:33.47,Default,,0000,0000,0000,,works. Before going into more detail about\Nwhy this method is so good at producing
Dialogue: 0,0:22:33.47,0:22:38.77,Default,,0000,0000,0000,,ultra short pulses, I'd like to mention\Nthat this is only possible because we have
Dialogue: 0,0:22:38.77,0:22:44.12,Default,,0000,0000,0000,,the high intensity driving pulses, the red\Nlaser pulses available. This goes back to
Dialogue: 0,0:22:44.12,0:22:47.27,Default,,0000,0000,0000,,work by Donna Strickland and Gerard\NMourou, who were awarded the Nobel Prize
Dialogue: 0,0:22:47.27,0:22:54.95,Default,,0000,0000,0000,,in the year 2018 in physics for this work\Nthat has been done in the 80s. Now we're
Dialogue: 0,0:22:54.95,0:22:59.69,Default,,0000,0000,0000,,coming to the only equation of his talk,\Nwhich is this equation that relates the
Dialogue: 0,0:22:59.69,0:23:07.50,Default,,0000,0000,0000,,energy width and the time duration of a\Nultra short pulse. By the law of fourier
Dialogue: 0,0:23:07.50,0:23:13.15,Default,,0000,0000,0000,,limits we cannot have pulses that are very\Nshort in time and at the same time very
Dialogue: 0,0:23:13.15,0:23:17.70,Default,,0000,0000,0000,,narrow in energy. But we need to choose\None. So if we want to have policies that
Dialogue: 0,0:23:17.70,0:23:23.64,Default,,0000,0000,0000,,are very short in time like the pulse that\NI've shown here on the bottom, that is
Dialogue: 0,0:23:23.64,0:23:26.67,Default,,0000,0000,0000,,actually only two hundred fifty\Nattoseconds long, so even shorter than a
Dialogue: 0,0:23:26.67,0:23:33.06,Default,,0000,0000,0000,,femtosecond, then we need to have a very\Nbroad width in energy. And this means
Dialogue: 0,0:23:33.06,0:23:37.45,Default,,0000,0000,0000,,combining a lot of different colors inside\Nof this pulse. And this is what makes high
Dialogue: 0,0:23:37.45,0:23:41.58,Default,,0000,0000,0000,,harmonic generation so efficient at\Ncreating ultra short pulses, because the
Dialogue: 0,0:23:41.58,0:23:47.42,Default,,0000,0000,0000,,spectrum that the colors that come out of\Nhigh harmonic generation are shown here
Dialogue: 0,0:23:47.42,0:23:52.08,Default,,0000,0000,0000,,and they really span a long width. So we\Nget a lot of different colors with about
Dialogue: 0,0:23:52.08,0:23:57.67,Default,,0000,0000,0000,,the same intensity. And you can think of\Nit like putting them all back together
Dialogue: 0,0:23:57.67,0:24:04.99,Default,,0000,0000,0000,,into one attosecond pulse. That is very\Nshort in time. This method has really made
Dialogue: 0,0:24:04.99,0:24:08.95,Default,,0000,0000,0000,,a big breakthrough in the generation of\Nultra short laser pulses we see here a
Dialogue: 0,0:24:08.95,0:24:15.30,Default,,0000,0000,0000,,plot of a time duration of laser pulses\Nversus the year, and we see that since the
Dialogue: 0,0:24:15.30,0:24:23.52,Default,,0000,0000,0000,,invention of the laser, here in the mid\N60s, there was a first technological
Dialogue: 0,0:24:23.52,0:24:28.92,Default,,0000,0000,0000,,progress and shorter and shorter pulses\Ncould be generated. But then in the 80s,
Dialogue: 0,0:24:28.92,0:24:34.40,Default,,0000,0000,0000,,there was a limit that had been reached of\Nabout five femtoseconds, I believe. And we
Dialogue: 0,0:24:34.40,0:24:39.71,Default,,0000,0000,0000,,could not really go farther than that and\Nonly with high harmonic generation, that
Dialogue: 0,0:24:39.71,0:24:45.42,Default,,0000,0000,0000,,sets in here shortly before the year 2000,\Nwe were able to generate pulses that are
Dialogue: 0,0:24:45.42,0:24:51.76,Default,,0000,0000,0000,,of a femtosecond duration. So that really\Ntouch the timescale of molecular motion.
Dialogue: 0,0:24:51.76,0:24:57.20,Default,,0000,0000,0000,,The current world record is a pulse, that\Nis only 43 attoseconds long, established
Dialogue: 0,0:24:57.20,0:25:02.29,Default,,0000,0000,0000,,in the year 2017. So that's really the\Ntimescale of electrons and we can do all
Dialogue: 0,0:25:02.29,0:25:06.65,Default,,0000,0000,0000,,sorts of nice experiments with it where we\Ndirectly observe electronic motion in
Dialogue: 0,0:25:06.65,0:25:12.47,Default,,0000,0000,0000,,atoms and molecules. This is all very\Nnice, but it has one limitation: We cannot
Dialogue: 0,0:25:12.47,0:25:17.17,Default,,0000,0000,0000,,go to hard X-rays, at least not right now.\NSo high harmonic generation cannot produce
Dialogue: 0,0:25:17.17,0:25:23.00,Default,,0000,0000,0000,,the kind of very short wavelengths that we\Nneed in order to to do X-ray diffraction
Dialogue: 0,0:25:23.00,0:25:29.43,Default,,0000,0000,0000,,experiments with atomic resolution. So if\Nwe want to have ultra short pulses that
Dialogue: 0,0:25:29.43,0:25:35.73,Default,,0000,0000,0000,,have X-Ray wavelengths, we need to build\Nright now very complex, very big machines,
Dialogue: 0,0:25:35.73,0:25:43.08,Default,,0000,0000,0000,,the so-called free electon lasers. Now,\Nthis would be a specific light source that
Dialogue: 0,0:25:43.08,0:25:48.06,Default,,0000,0000,0000,,can produce ultra short pulses with X-ray\Nwavelengths in itself. The X-Ray
Dialogue: 0,0:25:48.06,0:25:52.72,Default,,0000,0000,0000,,wavelengths is not so new. We know how to\Ntake X-ray images for about one hundred
Dialogue: 0,0:25:52.72,0:25:58.91,Default,,0000,0000,0000,,and thirty years and already in the 50s.\NRosalind Franklin, who is looking at a
Dialogue: 0,0:25:58.91,0:26:05.11,Default,,0000,0000,0000,,microscope here, was able to take a\Npicture of DNA, an X-ray diffraction
Dialogue: 0,0:26:05.11,0:26:11.88,Default,,0000,0000,0000,,pattern of a DNA double helix that was\Nsuccessful in revealing the double helix
Dialogue: 0,0:26:11.88,0:26:19.37,Default,,0000,0000,0000,,structure of our genetic code. But this is\Nnot a time resolved measurement. So think
Dialogue: 0,0:26:19.37,0:26:24.65,Default,,0000,0000,0000,,of it as you have a molecule that is in\Ncrystalline form, so it's not moving
Dialogue: 0,0:26:24.65,0:26:32.48,Default,,0000,0000,0000,,around and we can just take an X-ray image\Nof it, it's not going anywhere. But if we
Dialogue: 0,0:26:32.48,0:26:36.86,Default,,0000,0000,0000,,want - if we want to take a picture of\Nsomething that is moving, we need to have
Dialogue: 0,0:26:36.86,0:26:43.40,Default,,0000,0000,0000,,very short pulses. But we still need the\Nsame number of what we call photons, light
Dialogue: 0,0:26:43.40,0:26:48.89,Default,,0000,0000,0000,,particles. Or think of it as we need more\Nbrilliant X-ray flashes of light than we
Dialogue: 0,0:26:48.89,0:26:55.14,Default,,0000,0000,0000,,could obtain before. And there was very\Nnice technological development in the past
Dialogue: 0,0:26:55.14,0:27:01.69,Default,,0000,0000,0000,,50 years or so, where we were able to go\Nfrom the X-ray tube to newer light sources
Dialogue: 0,0:27:01.69,0:27:07.26,Default,,0000,0000,0000,,called Synchrotron, and today, free\Nelectro lasers that always increase the
Dialogue: 0,0:27:07.26,0:27:12.18,Default,,0000,0000,0000,,peak brilliance in an exponential way. So\Nwe can take really brilliant, really
Dialogue: 0,0:27:12.18,0:27:17.27,Default,,0000,0000,0000,,bright X-ray flashes right now. I cannot\Ngo into the details of all of that, but I
Dialogue: 0,0:27:17.27,0:27:21.35,Default,,0000,0000,0000,,found a very nice talk from two years ago,\Nbut actually explains everything from
Dialogue: 0,0:27:21.35,0:27:28.59,Default,,0000,0000,0000,,Synchrotron to FELs still available online\Nif you're interested in this work. And as
Dialogue: 0,0:27:28.59,0:27:32.11,Default,,0000,0000,0000,,always, if something is failing scaling\Nexponentially, most of you will be
Dialogue: 0,0:27:32.11,0:27:37.84,Default,,0000,0000,0000,,familiar with Moore's Law, that tells us\Nabout the exponential scaling of
Dialogue: 0,0:27:37.84,0:27:45.17,Default,,0000,0000,0000,,transistors. If something grows this fast,\Nit really opens up a new series of
Dialogue: 0,0:27:45.17,0:27:49.30,Default,,0000,0000,0000,,experiments of new technological\Napplications that no one has thought of
Dialogue: 0,0:27:49.30,0:27:55.60,Default,,0000,0000,0000,,before. And the same is true with free\Nelectron lasers. So I'm going to focus
Dialogue: 0,0:27:55.60,0:28:00.45,Default,,0000,0000,0000,,just on the most brilliant light sources\Nfor X-rays. Right now, the free electron
Dialogue: 0,0:28:00.45,0:28:06.23,Default,,0000,0000,0000,,lasers that are at the top right here of\Nthis graph have been around for maybe 10
Dialogue: 0,0:28:06.23,0:28:13.22,Default,,0000,0000,0000,,years or so. I cannot go into a lot of\Ndetail on how to generate ultrashort
Dialogue: 0,0:28:13.22,0:28:18.22,Default,,0000,0000,0000,,pulses with X-Rays. So I'd like to\Ngive you just a very broad picture of how
Dialogue: 0,0:28:18.22,0:28:23.91,Default,,0000,0000,0000,,this works. First, we need a bunch of\Nelectrons, that is accelerated to
Dialogue: 0,0:28:23.91,0:28:29.64,Default,,0000,0000,0000,,relativistic speed. This sounds very easy,\Nbut is actually part of a two kilometer
Dialogue: 0,0:28:29.64,0:28:35.49,Default,,0000,0000,0000,,long accelerator, that we have to build\Nand maintain. Now we have this bunch here
Dialogue: 0,0:28:35.49,0:28:41.23,Default,,0000,0000,0000,,of electrons shown in red and it's really\Nfast and now we can bring it into
Dialogue: 0,0:28:41.23,0:28:46.52,Default,,0000,0000,0000,,something that is called an undulator.\NThat's a series of alternating magnets,
Dialogue: 0,0:28:46.52,0:28:52.27,Default,,0000,0000,0000,,shown here in green on blue for the\Nalternating magnets. And you may remember,
Dialogue: 0,0:28:52.27,0:28:57.10,Default,,0000,0000,0000,,that when we put an electron, that is as a\Ncharged particle, into a magnetic field,
Dialogue: 0,0:28:57.10,0:29:02.82,Default,,0000,0000,0000,,the Lorence force will drive it away. And\Nif you have alternating magnets, then the
Dialogue: 0,0:29:02.82,0:29:08.89,Default,,0000,0000,0000,,electron will go on a sort of wiggly path\Nin this undulator. And the electron is a
Dialogue: 0,0:29:08.89,0:29:13.89,Default,,0000,0000,0000,,charged particle as it is wiggling around\Nwherever it turns around, it will emit
Dialogue: 0,0:29:13.89,0:29:18.31,Default,,0000,0000,0000,,radiation, that happens to be in the X-ray\Nregion of the electromagnetic spectrum,
Dialogue: 0,0:29:18.31,0:29:23.26,Default,,0000,0000,0000,,which is exactly what we want. We can\Nwatch this little movie here to see a
Dialogue: 0,0:29:23.26,0:29:28.80,Default,,0000,0000,0000,,better picture. So this is the undulating\Nseeing from the side. We now go inside of
Dialogue: 0,0:29:28.80,0:29:35.88,Default,,0000,0000,0000,,the undulator. We have a series of\Nalternating magnets. Now the electron
Dialogue: 0,0:29:35.88,0:29:42.43,Default,,0000,0000,0000,,bunch shows up and you see the wiggly\Nmotion as it passes the different magnets.
Dialogue: 0,0:29:42.43,0:29:48.39,Default,,0000,0000,0000,,And you see the bright X-Ray flash that is\Nformed and gets stronger and stronger as
Dialogue: 0,0:29:48.39,0:29:54.78,Default,,0000,0000,0000,,the electron bunch passes the undulator. So\Nwe need several of these magnet pairs to
Dialogue: 0,0:29:54.78,0:30:00.13,Default,,0000,0000,0000,,in the end, get the very bright X-Ray\Nflash. And at the end of the undulator we
Dialogue: 0,0:30:00.13,0:30:06.24,Default,,0000,0000,0000,,dump the electron, we don't really need\Nthis electron bunch anymore and continue
Dialogue: 0,0:30:06.24,0:30:13.83,Default,,0000,0000,0000,,with a very bright X-Ray flash. This whole\Nprocess is a bit stochastic in nature, but
Dialogue: 0,0:30:13.83,0:30:18.89,Default,,0000,0000,0000,,it's amplifying itself in because of the\Nundulator. This is why the longer the
Dialogue: 0,0:30:18.89,0:30:29.02,Default,,0000,0000,0000,,undulator is, the more bright X-Ray\Nflashes we can generate. This whole thing
Dialogue: 0,0:30:29.02,0:30:33.15,Default,,0000,0000,0000,,is kind of complicated to build, it's a\Nvery complex machine. So right now there
Dialogue: 0,0:30:33.15,0:30:37.74,Default,,0000,0000,0000,,are only very few free electron lasers in\Nthe world. First one in California called
Dialogue: 0,0:30:37.74,0:30:43.85,Default,,0000,0000,0000,,LCLS 1, currently being upgraded to LCLS\N2. There are several in Europe. There's
Dialogue: 0,0:30:43.85,0:30:49.33,Default,,0000,0000,0000,,one in Switzerland, in Italy and Hamburg.\NSo there's a Flash that does not operate
Dialogue: 0,0:30:49.33,0:30:54.56,Default,,0000,0000,0000,,in the hot X-ray regime, but was kind of\Nfirst free electron laser. That's the most
Dialogue: 0,0:30:54.56,0:30:58.92,Default,,0000,0000,0000,,recent addition to the free electron laser\Nzoo. It's the European XFEL also located
Dialogue: 0,0:30:58.92,0:31:04.40,Default,,0000,0000,0000,,in Hamburg. And then we have some of these\Nlight sources in Asia, in Korea, South
Dialogue: 0,0:31:04.40,0:31:10.73,Default,,0000,0000,0000,,Korea, Japan, and one currently under\Nconstruction in Shanghai. I'd like to show
Dialogue: 0,0:31:10.73,0:31:15.74,Default,,0000,0000,0000,,you a bit more details about the European\NX-ray free electron laser, because it's
Dialogue: 0,0:31:15.74,0:31:23.98,Default,,0000,0000,0000,,closest to us, and at least closest to\Nwhere I work. So the European XFEL is a
Dialogue: 0,0:31:23.98,0:31:30.05,Default,,0000,0000,0000,,three point four kilometer long machine\Nthat is funded by in total 12 countries,
Dialogue: 0,0:31:30.05,0:31:36.35,Default,,0000,0000,0000,,So Germany and Russia paying the most and\Nthen the other 10 countries also providing
Dialogue: 0,0:31:36.35,0:31:41.13,Default,,0000,0000,0000,,to the construction and maintenance costs.\NThis machine starts at the DESY campus,
Dialogue: 0,0:31:41.13,0:31:47.34,Default,,0000,0000,0000,,but as shown here to the right of the\Npicture. And then we have first an
Dialogue: 0,0:31:47.34,0:31:51.58,Default,,0000,0000,0000,,accelerator line for the electrons that\Nit's already one point seven kilometers
Dialogue: 0,0:31:51.58,0:31:58.45,Default,,0000,0000,0000,,long and where we add electrons reach\Ntheir relativistic speed. Then the
Dialogue: 0,0:31:58.45,0:32:04.60,Default,,0000,0000,0000,,undulate comes in, so the range of magnets\Nwhere we X-Ray flashes are produced. The x
Dialogue: 0,0:32:04.60,0:32:09.33,Default,,0000,0000,0000,,X-Ray flashes then cross the border to\NSchleswig-Holstein, {\i1}laughter {\i0} shown here, on the
Dialogue: 0,0:32:09.33,0:32:16.45,Default,,0000,0000,0000,,other side in a new federal state. They\Nreach the experimental hall. We have in
Dialogue: 0,0:32:16.45,0:32:21.05,Default,,0000,0000,0000,,total six experimental end stations at the\NEuropean XFEL that provide different
Dialogue: 0,0:32:21.05,0:32:24.42,Default,,0000,0000,0000,,instrumentation, depending on which kind\Nof system you want to study, you need
Dialogue: 0,0:32:24.42,0:32:30.96,Default,,0000,0000,0000,,slightly different instruments. And it's\Nnot only for taking molecular movies, but
Dialogue: 0,0:32:30.96,0:32:36.01,Default,,0000,0000,0000,,the XFEL is used, among others, for\Nmaterial science, for the imaging of bio
Dialogue: 0,0:32:36.01,0:32:40.95,Default,,0000,0000,0000,,molecules, for femtosecond chemistry, all\Nsorts of things. So really wide range of
Dialogue: 0,0:32:40.95,0:32:46.58,Default,,0000,0000,0000,,applications. It's right now the the\Nfastest such light source can take twenty
Dialogue: 0,0:32:46.58,0:32:51.58,Default,,0000,0000,0000,,seven thousand flashes per second, which\Nis great because every flash is one
Dialogue: 0,0:32:51.58,0:32:56.11,Default,,0000,0000,0000,,picture. So if we want to take a lot of\Nsnapshots, if you want to generate a lot
Dialogue: 0,0:32:56.11,0:33:01.18,Default,,0000,0000,0000,,of data in a short time, it's great to\Nhave as many flashes per second as
Dialogue: 0,0:33:01.18,0:33:08.72,Default,,0000,0000,0000,,possible. And as you can imagine, it's\Nkind of expensive since there are so few
Dialogue: 0,0:33:08.72,0:33:15.45,Default,,0000,0000,0000,,free electron lasers in the world to take\Nmeasurements there. The complete price tag
Dialogue: 0,0:33:15.45,0:33:19.92,Default,,0000,0000,0000,,for constructing this machine, it took\Neight years and cost one point two billion
Dialogue: 0,0:33:19.92,0:33:25.58,Default,,0000,0000,0000,,euros, which may seem a lot, but it's the\Nsame amount that we spend on concert halls
Dialogue: 0,0:33:25.58,0:33:39.03,Default,,0000,0000,0000,,in Hamburg. {\i1}loud laughter applause{\i0} So kind of comparable. Now,\Nwhen you factor in maintenance and so on,
Dialogue: 0,0:33:39.03,0:33:45.64,Default,,0000,0000,0000,,I think a minute of X-Ray beam at such an\NXFEL cost several thousands of tens of
Dialogue: 0,0:33:45.64,0:33:51.57,Default,,0000,0000,0000,,thousands of euros in the end. So getting\Nmeasurement time is complicated and there
Dialogue: 0,0:33:51.57,0:33:56.71,Default,,0000,0000,0000,,are committees that select the most\Nfruitful approaches and so on. So in order
Dialogue: 0,0:33:56.71,0:34:04.00,Default,,0000,0000,0000,,to not to waste or do taxpayers money.\NWith this, I'd like to make a small
Dialogue: 0,0:34:04.00,0:34:08.02,Default,,0000,0000,0000,,comparison of the light sources that I've\Nintroduced now. So I introduced the
Dialogue: 0,0:34:08.02,0:34:12.81,Default,,0000,0000,0000,,laboratory light sources and the XFEL\Nlight source. In general, in the
Dialogue: 0,0:34:12.81,0:34:17.60,Default,,0000,0000,0000,,laboratory we can generate very short\Npulses of less than 100 attoseconds by now
Dialogue: 0,0:34:17.60,0:34:22.98,Default,,0000,0000,0000,,and in the XFEL we are limited to\Nsomething about 10 femtoseconds right now.
Dialogue: 0,0:34:22.98,0:34:29.63,Default,,0000,0000,0000,,In terms of brilliance the XFELs can go to\Nmuch more bright pulses, simply because
Dialogue: 0,0:34:29.63,0:34:32.96,Default,,0000,0000,0000,,they are bigger machines and high harmonic\Ngeneration in itself is a kind of
Dialogue: 0,0:34:32.96,0:34:38.87,Default,,0000,0000,0000,,inefficient process. In terms of\Nwavelength X-Ray free electron lasers
Dialogue: 0,0:34:38.87,0:34:42.62,Default,,0000,0000,0000,,enable us to reach these very short\Nwavelengths with X-Rays, that we need to
Dialogue: 0,0:34:42.62,0:34:48.29,Default,,0000,0000,0000,,get atomic resolution of defractive\Nimages. In the laboratory we are a bit
Dialogue: 0,0:34:48.29,0:34:54.85,Default,,0000,0000,0000,,more limited to maybe the soft X-ray\Nregion. There's another important thing to
Dialogue: 0,0:34:54.85,0:34:59.89,Default,,0000,0000,0000,,keep in mind when we do experiments,\Nthat's the control of pulse parameters. So
Dialogue: 0,0:34:59.89,0:35:03.04,Default,,0000,0000,0000,,is every pulse that comes out of my\Nmachine the same as the one that came out
Dialogue: 0,0:35:03.04,0:35:08.52,Default,,0000,0000,0000,,of my machine before. And since the XFEL\Nproduces pulses by what is in the end, a
Dialogue: 0,0:35:08.52,0:35:13.63,Default,,0000,0000,0000,,stochastic process, that's not really the\Ncase. So the control of possible
Dialogue: 0,0:35:13.63,0:35:20.40,Default,,0000,0000,0000,,parameters is not really given. This is\Nmuch better in the laboratory. And in
Dialogue: 0,0:35:20.40,0:35:23.28,Default,,0000,0000,0000,,terms of cost and availability, it would\Nof course, be nice if we could do more
Dialogue: 0,0:35:23.28,0:35:29.62,Default,,0000,0000,0000,,experiments in the lab. Then at the XFEL\Nsimply because we XFEL ls so expensive to
Dialogue: 0,0:35:29.62,0:35:35.73,Default,,0000,0000,0000,,build and maintain and we have so few of\Nthem in the world. And you can see this
Dialogue: 0,0:35:35.73,0:35:41.84,Default,,0000,0000,0000,,tunnel here. It stretches for two\Nkilometers or so, all packed with very
Dialogue: 0,0:35:41.84,0:35:53.26,Default,,0000,0000,0000,,expensive equipment. So I'd like to show\Nyou a brief example of what we can learn
Dialogue: 0,0:35:53.26,0:35:58.50,Default,,0000,0000,0000,,in ultrafast science. So this is a\Ntheoretical work that we did in our group.
Dialogue: 0,0:35:58.50,0:36:03.72,Default,,0000,0000,0000,,So no experimental data, but still nice to\Nsee. This is concerned with an organic
Dialogue: 0,0:36:03.72,0:36:09.73,Default,,0000,0000,0000,,solar cell. So we all know solar cells.\NThey convert sunlight to electric energy
Dialogue: 0,0:36:09.73,0:36:14.48,Default,,0000,0000,0000,,that we can use in our devices. The nice\Nthing about organic solar cells is that
Dialogue: 0,0:36:14.48,0:36:20.90,Default,,0000,0000,0000,,they are foldable, very lightweight, and\Nwe can produce them cheaply. The way that
Dialogue: 0,0:36:20.90,0:36:25.63,Default,,0000,0000,0000,,such a solar cell works is we have light\Nshining in and at the bottom of the solar
Dialogue: 0,0:36:25.63,0:36:29.41,Default,,0000,0000,0000,,cell there sits an electrode that collects\Nall the charges and creates an electric
Dialogue: 0,0:36:29.41,0:36:33.57,Default,,0000,0000,0000,,current. Now light creates a charge that\Nsomehow needs to travel down there to this
Dialogue: 0,0:36:33.57,0:36:42.00,Default,,0000,0000,0000,,electrode and in fact, many of these\Ncharges. So the important thing where we
Dialogue: 0,0:36:42.00,0:36:46.64,Default,,0000,0000,0000,,build such an organic solar cell is that\Nwe need a way to efficiently transport
Dialogue: 0,0:36:46.64,0:36:55.24,Default,,0000,0000,0000,,these charges. And we can do so by putting\Npolymers inside. A polymer is just a
Dialogue: 0,0:36:55.24,0:36:59.67,Default,,0000,0000,0000,,molecule that is made up of two different\Nor two or more different smaller
Dialogue: 0,0:36:59.67,0:37:05.10,Default,,0000,0000,0000,,molecules. And one such polymer, which\Nshould be very efficient at transporting
Dialogue: 0,0:37:05.10,0:37:10.17,Default,,0000,0000,0000,,these charges is BT-1T, that is shown here\Nof a name is not so important, it's an
Dialogue: 0,0:37:10.17,0:37:15.08,Default,,0000,0000,0000,,abbreviation. Because in BT-1T when we\Ncreate a charge at one end of a molecule
Dialogue: 0,0:37:15.08,0:37:20.18,Default,,0000,0000,0000,,here at the top, it travels very quickly\Nto the other side of a molecule and you
Dialogue: 0,0:37:20.18,0:37:26.88,Default,,0000,0000,0000,,can imagine stacking several of these\NBT-1T or especially of the Ts together,
Dialogue: 0,0:37:26.88,0:37:31.17,Default,,0000,0000,0000,,putting it in this material. And then we\Nhave a very efficient flow of energy in
Dialogue: 0,0:37:31.17,0:37:41.88,Default,,0000,0000,0000,,our organic solar cell. So what we did was\Nwe calculated the ultrafast charge
Dialogue: 0,0:37:41.88,0:37:48.16,Default,,0000,0000,0000,,migration in BT-1T, shown here to the\Nright. The pink thing is the charge
Dialogue: 0,0:37:48.16,0:37:53.57,Default,,0000,0000,0000,,density that was created by an initial\Nionization of the molecule. And now I show
Dialogue: 0,0:37:53.57,0:37:58.11,Default,,0000,0000,0000,,you the movie, how this charge is moving\Naround in a molecule so you can see
Dialogue: 0,0:37:58.11,0:38:02.82,Default,,0000,0000,0000,,individual atoms moving, the whole\Nmolecules vibrating a bit. And the charge,
Dialogue: 0,0:38:02.82,0:38:10.57,Default,,0000,0000,0000,,if you look closely, is locating on the\Nright half of a molecule within about 250
Dialogue: 0,0:38:10.57,0:38:16.78,Default,,0000,0000,0000,,femtoseconds. Now, we cannot observe this\Ncharge migration directly by looking at
Dialogue: 0,0:38:16.78,0:38:21.29,Default,,0000,0000,0000,,this pink charge density that I've drawn\Nhere, because it's at least for us, not
Dialogue: 0,0:38:21.29,0:38:26.15,Default,,0000,0000,0000,,experimentally observable directly. So we\Nneed an indirect measurement, an X-Ray
Dialogue: 0,0:38:26.15,0:38:30.05,Default,,0000,0000,0000,,absorption spectroscopy that I showed you\Nin the beginning could be such a
Dialogue: 0,0:38:30.05,0:38:35.31,Default,,0000,0000,0000,,measurement. Because in the X-Ray\Nabsorption spectrum of BT-1T that I've
Dialogue: 0,0:38:35.31,0:38:41.03,Default,,0000,0000,0000,,shown here in the bottom left, we see\Ndistinct peaks depending on where the
Dialogue: 0,0:38:41.03,0:38:47.07,Default,,0000,0000,0000,,charge is located. Initially the charge is\Nlocated at the top sulfur atom here and
Dialogue: 0,0:38:47.07,0:38:53.78,Default,,0000,0000,0000,,this molecule and we will see a peek at\Nthis color. Once the charge moves away to
Dialogue: 0,0:38:53.78,0:38:58.06,Default,,0000,0000,0000,,the bottom of a molecule to the other\Nhalf, we will see a peak at the place
Dialogue: 0,0:38:58.06,0:39:02.68,Default,,0000,0000,0000,,where nothing is right now because the\Ncharge is not there. But if I start this
Dialogue: 0,0:39:02.68,0:39:09.60,Default,,0000,0000,0000,,movie, we will again see very fast charge\Ntransfer. So within about two hundred
Dialogue: 0,0:39:09.60,0:39:14.05,Default,,0000,0000,0000,,femtoseconds, the charge goes from one end\Nto the molecule to the other end of a
Dialogue: 0,0:39:14.05,0:39:19.47,Default,,0000,0000,0000,,molecule. And it would be really nice to\Nsee this in action in the future XFEL
Dialogue: 0,0:39:19.47,0:39:25.72,Default,,0000,0000,0000,,experiment. But the process is very long.\NYou need to apply for time at an XFEL. You
Dialogue: 0,0:39:25.72,0:39:29.85,Default,,0000,0000,0000,,need to evaluate all the data. So maybe a\Ncouple of years from now we will have the
Dialogue: 0,0:39:29.85,0:39:37.73,Default,,0000,0000,0000,,data available. Right now we are stuck\Nwith this movie, that we calculated. Now,
Dialogue: 0,0:39:37.73,0:39:43.59,Default,,0000,0000,0000,,towards the end of my talk, I'd like to go\Nbeyond the molecular movie. So I've shown
Dialogue: 0,0:39:43.59,0:39:47.86,Default,,0000,0000,0000,,you now how to generate the light pulses\Nand an example of what we can study with
Dialogue: 0,0:39:47.86,0:39:53.54,Default,,0000,0000,0000,,these light pulses. But this is not all we\Ncan do: So when you think of a chemical
Dialogue: 0,0:39:53.54,0:39:58.42,Default,,0000,0000,0000,,reaction, you might remember high school\Nchemistry or something like this, which is
Dialogue: 0,0:39:58.42,0:40:03.46,Default,,0000,0000,0000,,always foaming and exploding and nobody\Nreally knows what is going on. So a
Dialogue: 0,0:40:03.46,0:40:08.48,Default,,0000,0000,0000,,chemical reaction quite naturally involves\Nmolecular dynamics, for example, the
Dialogue: 0,0:40:08.48,0:40:13.18,Default,,0000,0000,0000,,decomposition of a molecule to go from\Nhere, from the left side to the right
Dialogue: 0,0:40:13.18,0:40:18.18,Default,,0000,0000,0000,,side, the molecules will somehow need to\Nrearrange so all the atoms will have moved
Dialogue: 0,0:40:18.18,0:40:24.34,Default,,0000,0000,0000,,quite a bit. We've seen already how we can\Ntrigger these chemical reactions or these
Dialogue: 0,0:40:24.34,0:40:29.77,Default,,0000,0000,0000,,molecular motion that was part of a\Nmolecular movie. But it would be really
Dialogue: 0,0:40:29.77,0:40:34.43,Default,,0000,0000,0000,,cool if we could control the reaction with\Nlight. So the way to do this, it's not
Dialogue: 0,0:40:34.43,0:40:38.92,Default,,0000,0000,0000,,currently something that is possible, but\Nmaybe in the near future, would be to
Dialogue: 0,0:40:38.92,0:40:44.44,Default,,0000,0000,0000,,implement a sort of optimisation feedback\Nloop. So we would record the fragments of
Dialogue: 0,0:40:44.44,0:40:48.97,Default,,0000,0000,0000,,our reaction, send it to an optimization\Nroutine that will also be quite
Dialogue: 0,0:40:48.97,0:40:53.62,Default,,0000,0000,0000,,complicated and will need to take into\Naccount the whole theory of how light and
Dialogue: 0,0:40:53.62,0:40:58.77,Default,,0000,0000,0000,,matter, interact and so on. And this\Noptimization routine would then generate a
Dialogue: 0,0:40:58.77,0:41:03.80,Default,,0000,0000,0000,,new sequence of ultra short pulses and\Nwith this feedback loop, it might be
Dialogue: 0,0:41:03.80,0:41:10.10,Default,,0000,0000,0000,,possible to find the right pulses to\Ncontrol chemical reactions, taking into
Dialogue: 0,0:41:10.10,0:41:17.64,Default,,0000,0000,0000,,account the quantum nature of this motion\Nand so on. Right now this is not possible.
Dialogue: 0,0:41:17.64,0:41:23.65,Default,,0000,0000,0000,,First, because the whole process of how we\Ncan generate these ultra short pulses is
Dialogue: 0,0:41:23.65,0:41:28.76,Default,,0000,0000,0000,,not so well controlled that we could\Nactually implement it in such a loop. And
Dialogue: 0,0:41:28.76,0:41:33.00,Default,,0000,0000,0000,,also the step optimization routine is more\Ncomplex than it looks like here in this
Dialogue: 0,0:41:33.00,0:41:39.49,Default,,0000,0000,0000,,picture. So this is something that people\Nare working on at the moment, but this
Dialogue: 0,0:41:39.49,0:41:44.30,Default,,0000,0000,0000,,would be something like the ultra fast\Nwishlist for next Christmas, not this
Dialogue: 0,0:41:44.30,0:41:49.71,Default,,0000,0000,0000,,Christmas. So we've succeeded in taking a\Nmolecular movie, but we would also like to
Dialogue: 0,0:41:49.71,0:41:55.27,Default,,0000,0000,0000,,be able to direct a molecular movie. So to\Ngo beyond just watching nature, but
Dialogue: 0,0:41:55.27,0:42:01.46,Default,,0000,0000,0000,,controlling nature because this is what\Nhumans like to best, {\i1} laughing{\i0} fortunately or
Dialogue: 0,0:42:01.46,0:42:06.23,Default,,0000,0000,0000,,unfortunately, it depends. So I'd like to\Njust show you that this is really an ultra
Dialogue: 0,0:42:06.23,0:42:12.22,Default,,0000,0000,0000,,fast developing field. There's lots of new\Nresearch papers every day, every week
Dialogue: 0,0:42:12.22,0:42:18.07,Default,,0000,0000,0000,,coming in, studying all sorts of systems.\NWhen you just take a quick and dirty
Dialogue: 0,0:42:18.07,0:42:22.82,Default,,0000,0000,0000,,metric of how important ultrafast science\Nis this is the number of articles per year
Dialogue: 0,0:42:22.82,0:42:28.50,Default,,0000,0000,0000,,that mentioned ultrafast in Google\NScholar, it's exponentially growing. At
Dialogue: 0,0:42:28.50,0:42:30.78,Default,,0000,0000,0000,,the same time, the number of total\Npublications in Google Scholar is more or
Dialogue: 0,0:42:30.78,0:42:34.99,Default,,0000,0000,0000,,less constant, so the blue line here\Noutgrows the green line considerably since
Dialogue: 0,0:42:34.99,0:42:45.07,Default,,0000,0000,0000,,about ten years. So what remains to be\Ndone? We've seen that we have light
Dialogue: 0,0:42:45.07,0:42:50.02,Default,,0000,0000,0000,,sources available to generate ultra short\Npulses, but as always, when you have
Dialogue: 0,0:42:50.02,0:42:55.54,Default,,0000,0000,0000,,better machines, bigger machines, you can\Ntake more fancy experiments. So it would
Dialogue: 0,0:42:55.54,0:43:00.58,Default,,0000,0000,0000,,be really nice to develop both lab based\Nsources and free electron laser sources so
Dialogue: 0,0:43:00.58,0:43:06.36,Default,,0000,0000,0000,,that we can take more, more interesting,\Nmore complex experiments. Another
Dialogue: 0,0:43:06.36,0:43:10.06,Default,,0000,0000,0000,,important challenge, that's what people in\Nmy research group where I work are working
Dialogue: 0,0:43:10.06,0:43:16.75,Default,,0000,0000,0000,,on is to improve theoretical calculations\Nbecause I did not go into a lot of detail
Dialogue: 0,0:43:16.75,0:43:21.73,Default,,0000,0000,0000,,on how to calculate these things, but it's\Nessentially quantum mechanics and quantum
Dialogue: 0,0:43:21.73,0:43:26.53,Default,,0000,0000,0000,,mechanics skales very unfavorably. So\Ngoing from a very small molecule like the
Dialogue: 0,0:43:26.53,0:43:32.49,Default,,0000,0000,0000,,glycene molecule here to something like a\Nprotein is not doable. Simply, it cannot
Dialogue: 0,0:43:32.49,0:43:38.10,Default,,0000,0000,0000,,compute this with quantum mechanics. So we\Nneed all sorts of new methodology to -
Dialogue: 0,0:43:38.10,0:43:45.10,Default,,0000,0000,0000,,Yeah - to better describe larger systems.\NWe would in general like to study not only
Dialogue: 0,0:43:45.10,0:43:49.41,Default,,0000,0000,0000,,small molecules and not only take movies\Nof small molecules, but really study large
Dialogue: 0,0:43:49.41,0:43:55.71,Default,,0000,0000,0000,,systems like this is the FMO complex, that\Nis a central in photosynthesis or solid
Dialogue: 0,0:43:55.71,0:44:01.41,Default,,0000,0000,0000,,states that are here shown in this crystal\Nstructure simply because this is more
Dialogue: 0,0:44:01.41,0:44:07.79,Default,,0000,0000,0000,,interesting for biological, chemical\Napplications. And finally, as I've shown
Dialogue: 0,0:44:07.79,0:44:13.46,Default,,0000,0000,0000,,you, it would be cool to directly control\Nchemical reactions with light. So to find
Dialogue: 0,0:44:13.46,0:44:20.81,Default,,0000,0000,0000,,a way how to replace this mess with a\Nclean light pulse. With this, I'm at the
Dialogue: 0,0:44:20.81,0:44:26.24,Default,,0000,0000,0000,,end. I'd like to quickly summarize\Nfemtodynamics, really fundamental in
Dialogue: 0,0:44:26.24,0:44:31.50,Default,,0000,0000,0000,,biology, chemistry and physics. So more or\Nless, the origin of life is on this
Dialogue: 0,0:44:31.50,0:44:36.84,Default,,0000,0000,0000,,timescale. We can take molecular movies\Nwith ultrashort laser pulses and we can
Dialogue: 0,0:44:36.84,0:44:41.65,Default,,0000,0000,0000,,generate these pulses in the laboratory or\Nadd free electron lasers with different
Dialogue: 0,0:44:41.65,0:44:46.82,Default,,0000,0000,0000,,characteristics. And we would like to not\Nonly understand these ultra fast
Dialogue: 0,0:44:46.82,0:44:51.92,Default,,0000,0000,0000,,phenomena, but we would also like to be\Nable to control them in the future. With
Dialogue: 0,0:44:51.92,0:44:54.16,Default,,0000,0000,0000,,this, I'd like to thank you for your\Nattention and thank the supporting
Dialogue: 0,0:44:54.16,0:45:04.57,Default,,0000,0000,0000,,institutions here that funded my PhD work.
Dialogue: 0,0:45:04.57,0:45:10.82,Default,,0000,0000,0000,,{\i1}applause{\i0}
Dialogue: 0,0:45:10.82,0:45:17.38,Default,,0000,0000,0000,,Herald: Well, that was an interesting\Ntalk. I enjoyed it very much. I guess this
Dialogue: 0,0:45:17.38,0:45:23.45,Default,,0000,0000,0000,,will spark some questions. If you want to\Nask Caroline a question, please line up
Dialogue: 0,0:45:23.45,0:45:28.90,Default,,0000,0000,0000,,behind the microphones. We have three in\Nthe isles between the seats if you want to
Dialogue: 0,0:45:28.90,0:45:36.07,Default,,0000,0000,0000,,leave, please do so in the door here in\Nthe front. And until we get questions from
Dialogue: 0,0:45:36.07,0:45:39.57,Default,,0000,0000,0000,,the audience, do we have questions from\Nthe Internet?
Dialogue: 0,0:45:39.57,0:45:45.31,Default,,0000,0000,0000,,Signal angel: Yes. Big fat random user is\Ncurious about the design of the X-Ray
Dialogue: 0,0:45:45.31,0:45:48.46,Default,,0000,0000,0000,,detector. Do you have any information on\Nthat?
Dialogue: 0,0:45:48.46,0:45:56.03,Default,,0000,0000,0000,,Caroline: That's also very complex. I'm\Nnot a big expert in detectors. At this
Dialogue: 0,0:45:56.03,0:45:58.46,Default,,0000,0000,0000,,point, I really recommend watching the\Ntalk from two years ago, that explains a
Dialogue: 0,0:45:58.46,0:46:05.14,Default,,0000,0000,0000,,lot more about the X-Ray detectors. So\Nwhat I know about the X-Ray detector is
Dialogue: 0,0:46:05.14,0:46:09.99,Default,,0000,0000,0000,,that it's very complicated to process all\Nthe data because when you have 27000
Dialogue: 0,0:46:09.99,0:46:16.37,Default,,0000,0000,0000,,flashes of light, it produces, I think\Nterabytes of data within seconds and you
Dialogue: 0,0:46:16.37,0:46:21.03,Default,,0000,0000,0000,,need to somehow be able to store them and\Nanalyze them. So there is also a lot of
Dialogue: 0,0:46:21.03,0:46:24.19,Default,,0000,0000,0000,,technology involved in the design of these\Ndetectors.
Dialogue: 0,0:46:24.19,0:46:30.06,Default,,0000,0000,0000,,Herald: Thank you. So the first question\Nfrom microphone 2 in the middle.
Dialogue: 0,0:46:30.06,0:46:34.11,Default,,0000,0000,0000,,Microphone 2: So my question is.\NHerald: Please go close to the microphone.
Dialogue: 0,0:46:34.11,0:46:38.86,Default,,0000,0000,0000,,Microphone 2: My question is regarding the\Nsynchronization of the detector units when
Dialogue: 0,0:46:38.86,0:46:45.03,Default,,0000,0000,0000,,you're pointing to free electron laser so\Nyou can achieve this in synchronization.
Dialogue: 0,0:46:45.03,0:46:50.70,Default,,0000,0000,0000,,Caroline: This is also very complicated.\NIt's easier to do in the lab. So you're
Dialogue: 0,0:46:50.70,0:46:54.80,Default,,0000,0000,0000,,talking about the synchronization of\Nessentially the first pulse and the second
Dialogue: 0,0:46:54.80,0:47:00.54,Default,,0000,0000,0000,,pulse. Right. So in the lab, you typically\Ngenerate the second pulse from part of the
Dialogue: 0,0:47:00.54,0:47:05.31,Default,,0000,0000,0000,,first pulse. So you have a very natural\Nalignment, at least in time of these two
Dialogue: 0,0:47:05.31,0:47:10.19,Default,,0000,0000,0000,,pulses. The X-ray free electron lasers\Nhave special timing tools that allow you
Dialogue: 0,0:47:10.19,0:47:16.83,Default,,0000,0000,0000,,to find out how much is the time delay\Nbetween your two pulses. But it's true
Dialogue: 0,0:47:16.83,0:47:21.52,Default,,0000,0000,0000,,that this is complicated to achieve and\Nthis limits the experimental time
Dialogue: 0,0:47:21.52,0:47:25.86,Default,,0000,0000,0000,,resolution to something that is even\Nlarger than the time duration of the
Dialogue: 0,0:47:25.86,0:47:30.54,Default,,0000,0000,0000,,pulses.\NHerald: So now next question from
Dialogue: 0,0:47:30.54,0:47:35.93,Default,,0000,0000,0000,,microphone number 3.\NMicrophone 3: Yes, i remember in the
Dialogue: 0,0:47:35.93,0:47:42.81,Default,,0000,0000,0000,,beginning, you explained that your\Nmeasuring method usually destroys your
Dialogue: 0,0:47:42.81,0:47:49.70,Default,,0000,0000,0000,,molecules. That's a bit of a contradiction\Nto your idea to control. {\i1}laughing{\i0}
Dialogue: 0,0:47:49.70,0:47:59.09,Default,,0000,0000,0000,,Caroline: In principle, yes. But, so in\Nthe case of control, we would like to use
Dialogue: 0,0:47:59.09,0:48:04.65,Default,,0000,0000,0000,,a second pulse, that does not destroy the\Nmolecule. But for example, at least
Dialogue: 0,0:48:04.65,0:48:11.14,Default,,0000,0000,0000,,destroys it in a controlled way, for\Nexample. {\i1}loud laughter{\i0} So there's a difference between
Dialogue: 0,0:48:11.14,0:48:15.25,Default,,0000,0000,0000,,just blowing up your molecule and breaking\Napart a certain part, but yet that we are
Dialogue: 0,0:48:15.25,0:48:19.77,Default,,0000,0000,0000,,interested in. And that's what we would\Nlike to do in the control case. So we
Dialogue: 0,0:48:19.77,0:48:24.49,Default,,0000,0000,0000,,would like to be able to to control, for\Nexample, the fragmentation of a molecule
Dialogue: 0,0:48:24.49,0:48:30.23,Default,,0000,0000,0000,,such that we only get the important part\Nout and everything else just goes away.
Dialogue: 0,0:48:30.23,0:48:34.43,Default,,0000,0000,0000,,Microphone3: Thank you.\NHerald: So then another question for
Dialogue: 0,0:48:34.43,0:48:39.24,Default,,0000,0000,0000,,microphone 2 in the middle.\NMicrophone 2: So thank you for the talk. I
Dialogue: 0,0:48:39.24,0:48:44.47,Default,,0000,0000,0000,,was interested in how large structures or\Nmolecules can you imagine with this lab
Dialogue: 0,0:48:44.47,0:48:48.52,Default,,0000,0000,0000,,contributions and with this XFEL thing?\NCaroline: Sorry. Can you repeat?
Dialogue: 0,0:48:48.52,0:48:54.79,Default,,0000,0000,0000,,Microphone 2: So how large molecules can\Nyou imagine in this laboratory with this
Dialogue: 0,0:48:54.79,0:48:59.12,Default,,0000,0000,0000,,high harmonic measures?\NCaroline: So how large is not really the
Dialogue: 0,0:48:59.12,0:49:05.63,Default,,0000,0000,0000,,fundamental problem? People have taken\Nsnapshots of viruses or bigger bio
Dialogue: 0,0:49:05.63,0:49:11.87,Default,,0000,0000,0000,,molecules. If you want to - the problem is\Nrather how small can we get? So yeah, to
Dialogue: 0,0:49:11.87,0:49:16.37,Default,,0000,0000,0000,,take pictures of a very small molecule.\NCurrently we cannot take a picture of an
Dialogue: 0,0:49:16.37,0:49:21.78,Default,,0000,0000,0000,,individual small molecule, but what people\Ndo is they create crystals of a small
Dialogue: 0,0:49:21.78,0:49:25.26,Default,,0000,0000,0000,,molecule, sticking several of them\Ntogether and then taking images of this
Dialogue: 0,0:49:25.26,0:49:30.37,Default,,0000,0000,0000,,whole crystal for single particles, I\Nthink right now about the scale of a virus
Dialogue: 0,0:49:30.37,0:49:34.18,Default,,0000,0000,0000,,nanometers.\NMicrophone 2: Thank you.
Dialogue: 0,0:49:34.18,0:49:38.19,Default,,0000,0000,0000,,Herald: OK. Do we have another question\Nfrom the Internet?
Dialogue: 0,0:49:38.19,0:49:43.74,Default,,0000,0000,0000,,Signal Angel: We have. So this is\Nconcerning your permanent destruction of
Dialogue: 0,0:49:43.74,0:49:49.45,Default,,0000,0000,0000,,forces, I guess. How do you isolate single\Natoms and molecules for analysing between
Dialogue: 0,0:49:49.45,0:49:55.86,Default,,0000,0000,0000,,the different exposures?\NCaroline: Yes, excellent question. So
Dialogue: 0,0:49:55.86,0:50:01.44,Default,,0000,0000,0000,,molecules can be made available in the gas\Nphase by - so if you have them in a solid
Dialogue: 0,0:50:01.44,0:50:08.03,Default,,0000,0000,0000,,somewhere and you heat that up, they will\Nevaporate from that surface. This is how
Dialogue: 0,0:50:08.03,0:50:11.76,Default,,0000,0000,0000,,you can get them in the gas phase. This,\Nof course, assumes that you have a
Dialogue: 0,0:50:11.76,0:50:15.94,Default,,0000,0000,0000,,molecule, that is actually stable in the\Ngas space, which is not true for all
Dialogue: 0,0:50:15.94,0:50:22.45,Default,,0000,0000,0000,,molecules. And then the, the hard thing is\Nto align all three things. So the pump
Dialogue: 0,0:50:22.45,0:50:27.54,Default,,0000,0000,0000,,pulse, the probe pulse and the molecule\Nall need to be there at the same time.
Dialogue: 0,0:50:27.54,0:50:32.60,Default,,0000,0000,0000,,There are people doing whole PhD theses on\Nhow to design gas nozzles that can provide
Dialogue: 0,0:50:32.60,0:50:37.67,Default,,0000,0000,0000,,this stream of molecules.\NSignal Angel: So you basically really
Dialogue: 0,0:50:37.67,0:50:41.19,Default,,0000,0000,0000,,having a stream coming from a nozzle?\NCaroline: Yes.
Dialogue: 0,0:50:41.19,0:50:43.30,Default,,0000,0000,0000,,Signal Angel: It's a very thin stream, I\Nguess.
Dialogue: 0,0:50:43.30,0:50:47.62,Default,,0000,0000,0000,,Caroline: Yes.\NSignal Angel: Then you're exposing it like
Dialogue: 0,0:50:47.62,0:50:49.99,Default,,0000,0000,0000,,in a regular interval.\NCaroline: And of course you try to hit as
Dialogue: 0,0:50:49.99,0:50:56.18,Default,,0000,0000,0000,,many molecules as possible. So this is\Nespecially important when you do pictures
Dialogue: 0,0:50:56.18,0:50:59.76,Default,,0000,0000,0000,,of crystallized molecules because\Ncrystallizing these molecules is a lot of
Dialogue: 0,0:50:59.76,0:51:04.48,Default,,0000,0000,0000,,work. You don't want to waste like 99\Npercent that just fall away and you never
Dialogue: 0,0:51:04.48,0:51:07.99,Default,,0000,0000,0000,,take snapshots of them.\NSignal Angel: Thanks.
Dialogue: 0,0:51:07.99,0:51:10.99,Default,,0000,0000,0000,,Herald: So another question from\Nmicrophone 3.
Dialogue: 0,0:51:10.99,0:51:18.81,Default,,0000,0000,0000,,Microphone 3: How do you construct this\Nmovie? I mean, for every pulse to have a
Dialogue: 0,0:51:18.81,0:51:25.24,Default,,0000,0000,0000,,new molecule and for every molecule is\Noriented differently in space and has
Dialogue: 0,0:51:25.24,0:51:31.19,Default,,0000,0000,0000,,different oscillation modes. How do\Ncorrelate them? I mean, in the movie, I
Dialogue: 0,0:51:31.19,0:51:35.10,Default,,0000,0000,0000,,mean, every molecule is different than the\Nprevious one.
Dialogue: 0,0:51:35.10,0:51:41.40,Default,,0000,0000,0000,,Caroline: Yes. Excellent question. That's,\NSo first, what people can do is align
Dialogue: 0,0:51:41.40,0:51:48.43,Default,,0000,0000,0000,,molecules. So especially molecules that\Nare more or less linear. You can force
Dialogue: 0,0:51:48.43,0:51:55.41,Default,,0000,0000,0000,,them to be oriented in a certain way. And\Nthen there's also a bit of a secret in the
Dialogue: 0,0:51:55.41,0:52:00.22,Default,,0000,0000,0000,,trigger pulse that first sets off this\Nmotion. For example, if this trigger pulse
Dialogue: 0,0:52:00.22,0:52:04.60,Default,,0000,0000,0000,,is a very strong proto ionization, then\Nthis will kill off any sorts of
Dialogue: 0,0:52:04.60,0:52:08.91,Default,,0000,0000,0000,,vibrational states that you have had\Nbefore in the molecule. So in this sense,
Dialogue: 0,0:52:08.91,0:52:12.84,Default,,0000,0000,0000,,the trigger parts really defines a time\Nzero, that should be reproducible for any
Dialogue: 0,0:52:12.84,0:52:17.95,Default,,0000,0000,0000,,molecule that shows up in the stream and\Nthe rest is statistics.
Dialogue: 0,0:52:17.95,0:52:23.58,Default,,0000,0000,0000,,Microphone 3: Thank you.\NHerald: So there's another question on
Dialogue: 0,0:52:23.58,0:52:27.07,Default,,0000,0000,0000,,microphone 3.\NMicrophone 3: Are there any pre pulses or
Dialogue: 0,0:52:27.07,0:52:31.42,Default,,0000,0000,0000,,ghosts, You need to get rid of?\NCaroline: Sorry. Again.
Dialogue: 0,0:52:31.42,0:52:36.55,Default,,0000,0000,0000,,Microphone 3: You have to control pre\Npulses or ghosts during this effect for
Dialogue: 0,0:52:36.55,0:52:39.56,Default,,0000,0000,0000,,measurement.\NCaroline: That I'm not really sure of,
Dialogue: 0,0:52:39.56,0:52:42.09,Default,,0000,0000,0000,,since I'm not really conducting\Nexperiments, but probably.
Dialogue: 0,0:52:42.09,0:52:49.51,Default,,0000,0000,0000,,Herald: And another one from the middle,\Nfrom microphone 2 please.
Dialogue: 0,0:52:49.51,0:52:55.43,Default,,0000,0000,0000,,Microphone 2: I suppose if you apply for\Nexperimentation time at the XFEL laser,
Dialogue: 0,0:52:55.43,0:53:02.00,Default,,0000,0000,0000,,you have to submit very detailed plans and\Ntime lines and everything. And you will
Dialogue: 0,0:53:02.00,0:53:07.95,Default,,0000,0000,0000,,get the time window for your experiment, I\Nguess. what's going to happen if you're
Dialogue: 0,0:53:07.95,0:53:13.76,Default,,0000,0000,0000,,not completely finished within that time\Nwindow? Are they easy possibilities to
Dialogue: 0,0:53:13.76,0:53:19.18,Default,,0000,0000,0000,,extend the time or are they do they just\Nsay, well, you had your three weeks,
Dialogue: 0,0:53:19.18,0:53:23.12,Default,,0000,0000,0000,,you're out apply in 2026?\NCaroline: Yeah, I think it's a regular
Dialogue: 0,0:53:23.12,0:53:26.93,Default,,0000,0000,0000,,case, that you're not finished with your\Nexperiments by the time your beam time
Dialogue: 0,0:53:26.93,0:53:31.87,Default,,0000,0000,0000,,ends. That's how it usually goes. It's\Nalso unfortunatly not free weeks, but it's
Dialogue: 0,0:53:31.87,0:53:38.53,Default,,0000,0000,0000,,rather like 60 hours delivered in five\Nshifts of twelve hours. So, yeah, you
Dialogue: 0,0:53:38.53,0:53:43.25,Default,,0000,0000,0000,,write a very detailed proposal of what you\Nwould like to do. Submit it to a panel of
Dialogue: 0,0:53:43.25,0:53:50.62,Default,,0000,0000,0000,,experts, both scientists and technicians.\NSo they decide, is it interesting enough
Dialogue: 0,0:53:50.62,0:53:54.98,Default,,0000,0000,0000,,from a scientific point of view and is it\Nfeasible from a technical point of view?
Dialogue: 0,0:53:54.98,0:54:00.32,Default,,0000,0000,0000,,And then once you are there, you more or\Nless set up your experiment and do as much
Dialogue: 0,0:54:00.32,0:54:06.49,Default,,0000,0000,0000,,as you can. If you want to come back, you\Nneed to submit an additional proposal. So,
Dialogue: 0,0:54:06.49,0:54:10.59,Default,,0000,0000,0000,,yeah, I think most experimental groups try\Nto have several of these proposals running
Dialogue: 0,0:54:10.59,0:54:15.49,Default,,0000,0000,0000,,at the same time, so that there is not a\Ntwo year delay between your data
Dialogue: 0,0:54:15.49,0:54:21.07,Default,,0000,0000,0000,,acquisition. But yes. No possibility to\Nextend. It's booked already for the
Dialogue: 0,0:54:21.07,0:54:27.89,Default,,0000,0000,0000,,complete next year. The schedule is fixed.\NHerald: So I don't see any more people
Dialogue: 0,0:54:27.89,0:54:33.06,Default,,0000,0000,0000,,queuing up. If you want to pose a\Nquestion, please do so now. In the
Dialogue: 0,0:54:33.06,0:54:35.46,Default,,0000,0000,0000,,meantime, I would ask the signal angel if\Nthere's another question from the
Dialogue: 0,0:54:35.46,0:54:38.24,Default,,0000,0000,0000,,Internet.\NSignal Angel: I have a question about the
Dialogue: 0,0:54:38.24,0:54:44.65,Default,,0000,0000,0000,,dimensions of all those machines. The\Nundulator seems to be rather long and
Dialogue: 0,0:54:44.65,0:54:48.91,Default,,0000,0000,0000,,contain a lot of magnets. Do you have an\Nidea how long it is and how many of those
Dialogue: 0,0:54:48.91,0:54:55.22,Default,,0000,0000,0000,,electromagnets are in there?\NCaroline: Yeah. Sorry, I didn't mention
Dialogue: 0,0:54:55.22,0:54:57.22,Default,,0000,0000,0000,,it. It's about, I think one hundred and\Nseventy meters long in the case of the
Dialogue: 0,0:54:57.22,0:55:03.39,Default,,0000,0000,0000,,European XFEL. I'm not sure about the\Ndimension of the individual magnets, but
Dialogue: 0,0:55:03.39,0:55:09.10,Default,,0000,0000,0000,,it's probably also in the hundreds of\Nmagnets, magnet pairs.
Dialogue: 0,0:55:09.10,0:55:16.08,Default,,0000,0000,0000,,Herald: So is there more - excuse me,\Nthere is a question on the microphone
Dialogue: 0,0:55:16.08,0:55:20.35,Default,,0000,0000,0000,,number 3.\NMicrophone 3: Yeah. Hi. It's regarding the
Dialogue: 0,0:55:20.35,0:55:22.35,Default,,0000,0000,0000,,harmonic light.\NHerald: Please go closer to the
Dialogue: 0,0:55:22.35,0:55:24.35,Default,,0000,0000,0000,,microphone.\NMicrophone 3: The harmonic light generator
Dialogue: 0,0:55:24.35,0:55:26.87,Default,,0000,0000,0000,,that you were showing at the very\Nbeginning, just before the one that won
Dialogue: 0,0:55:26.87,0:55:32.70,Default,,0000,0000,0000,,the Nobel Prize. And can you also produce\Nlight in the visible range? Or it has to
Dialogue: 0,0:55:32.70,0:55:38.05,Default,,0000,0000,0000,,be in the visible range?\NCaroline: The high harmonic generation? So
Dialogue: 0,0:55:38.05,0:55:43.16,Default,,0000,0000,0000,,in the in the visible range, you cannot\Ncreate pulses that are so short that they
Dialogue: 0,0:55:43.16,0:55:50.96,Default,,0000,0000,0000,,would be interesting for what I'm doing.\NThe pulse that comes in is already quite
Dialogue: 0,0:55:50.96,0:55:54.79,Default,,0000,0000,0000,,short. So it's already femtoseconds long.\NThey just convert it into something that
Dialogue: 0,0:55:54.79,0:56:01.85,Default,,0000,0000,0000,,is fractions of a femtosecond long. And\Nyeah. In the indivisible range that's kind
Dialogue: 0,0:56:01.85,0:56:05.80,Default,,0000,0000,0000,,of a limit how short your pulse can be.\NMicrophone 3: So it is not a good
Dialogue: 0,0:56:05.80,0:56:11.06,Default,,0000,0000,0000,,candidate for hyperspectral light source.\NWe need another kind of technique, I
Dialogue: 0,0:56:11.06,0:56:16.36,Default,,0000,0000,0000,,guess.\NCaroline: Well, I mean you are kind of
Dialogue: 0,0:56:16.36,0:56:21.07,Default,,0000,0000,0000,,limited what short pulses you can generate\Nwith which wavelength.
Dialogue: 0,0:56:21.07,0:56:26.44,Default,,0000,0000,0000,,Microphone 3: Thank you.\NHerald: So again, a question to the Signal
Dialogue: 0,0:56:26.44,0:56:29.02,Default,,0000,0000,0000,,Angel. Are there more questions from the\Ninternet?
Dialogue: 0,0:56:29.02,0:56:34.59,Default,,0000,0000,0000,,Signal Angel: Yes I have another one about\Nthe lifetime of the molecules in the beam?
Dialogue: 0,0:56:34.59,0:56:39.80,Default,,0000,0000,0000,,How fast are they degrading or how fast\Nare they destructed?
Dialogue: 0,0:56:39.80,0:56:44.29,Default,,0000,0000,0000,,Caroline: So probably the question is\Nabout how fast they are destructed before
Dialogue: 0,0:56:44.29,0:56:53.42,Default,,0000,0000,0000,,- so either before our pulses hit the\Nmolecule the molecules should be stable
Dialogue: 0,0:56:53.42,0:56:57.33,Default,,0000,0000,0000,,enough to survive in the gas phase from\Nthe point where they are evaporated until
Dialogue: 0,0:56:57.33,0:57:01.37,Default,,0000,0000,0000,,the point where the pump and the probe\Npulse come together, because otherwise it
Dialogue: 0,0:57:01.37,0:57:07.56,Default,,0000,0000,0000,,doesn't make sense to study this molecule\Nin the gas phase. When the probe pulse
Dialogue: 0,0:57:07.56,0:57:12.69,Default,,0000,0000,0000,,hits and it flows apart, I guess pico\Nseconds until the whole molecules ...
Dialogue: 0,0:57:12.69,0:57:21.78,Default,,0000,0000,0000,,Microphone 3: Like instantaneous.\NHerald: So I don't see any more questions
Dialogue: 0,0:57:21.78,0:57:26.04,Default,,0000,0000,0000,,on the microphones and we have a few\Nminutes left. So if there are more
Dialogue: 0,0:57:26.04,0:57:30.03,Default,,0000,0000,0000,,questions from the Internet, we can take\Nmaybe one or two more.
Dialogue: 0,0:57:30.03,0:57:42.56,Default,,0000,0000,0000,,Signal Angel: Give me a second.\NHerald: For people leaving already, please
Dialogue: 0,0:57:42.56,0:57:46.76,Default,,0000,0000,0000,,look if you have taken trash and bottles\Nwith you.
Dialogue: 0,0:57:46.76,0:57:52.39,Default,,0000,0000,0000,,Signal Angel: So this one very, very\Ntechnical question. How do you compensate
Dialogue: 0,0:57:52.39,0:57:58.21,Default,,0000,0000,0000,,the electronic signal that the electronic\Nsignal reaction is probably slower than x
Dialogue: 0,0:57:58.21,0:58:05.24,Default,,0000,0000,0000,,ray or light or spectrum changes at one\Nmoment or at one particular moment, that
Dialogue: 0,0:58:05.24,0:58:10.17,Default,,0000,0000,0000,,was interesting to analyze. I do not\Nunderstand the question, though.
Dialogue: 0,0:58:10.17,0:58:13.24,Default,,0000,0000,0000,,Caroline: I think I understand the\Nquestion, but I don't have the answer
Dialogue: 0,0:58:13.24,0:58:16.86,Default,,0000,0000,0000,,because again, I'm a - that's the problem\Nof speaking to a technical audience, you
Dialogue: 0,0:58:16.86,0:58:23.71,Default,,0000,0000,0000,,get a lot of these very technical\Nquestion. Yeah. The data analysis is not
Dialogue: 0,0:58:23.71,0:58:32.81,Default,,0000,0000,0000,,instantaneous. So the data is transported\Nsomewhere safe in my imagination. And then
Dialogue: 0,0:58:32.81,0:58:37.18,Default,,0000,0000,0000,,taken from there. So this data analysis\Ndoes not have to take place on the same
Dialogue: 0,0:58:37.18,0:58:41.33,Default,,0000,0000,0000,,timescale as the data acquisition, which I\Nguess is also because of the problem that
Dialogue: 0,0:58:41.33,0:58:47.53,Default,,0000,0000,0000,,was mentioned in the question.\NHerald: I might interrupt here. Maybe it's
Dialogue: 0,0:58:47.53,0:58:55.68,Default,,0000,0000,0000,,also about the signal transmission, like\Nthe signal rising of the signal of the
Dialogue: 0,0:58:55.68,0:59:01.90,Default,,0000,0000,0000,,electrical signal transmissions. Because\Nthis would probably require bandwidths of
Dialogue: 0,0:59:01.90,0:59:06.68,Default,,0000,0000,0000,,several megahertz, gigahertz, I don't\Nknow, to transport these very fast
Dialogue: 0,0:59:06.68,0:59:09.68,Default,,0000,0000,0000,,results.\NCaroline: Yeah. I think that's also a
Dialogue: 0,0:59:09.68,0:59:15.13,Default,,0000,0000,0000,,problem of constructing the right\Ndetector. That has been solved apparently
Dialogue: 0,0:59:15.13,0:59:20.69,Default,,0000,0000,0000,,because they can take these images. {\i1}laughter{\i0}\NHerald: And on the other hand, we have 10
Dialogue: 0,0:59:20.69,0:59:28.76,Default,,0000,0000,0000,,gigabit either nets. So we get faster and\Nfaster electronics. More questions from
Dialogue: 0,0:59:28.76,0:59:39.92,Default,,0000,0000,0000,,the Internet? Does not look like it, also\Nthe time is running out. So let's thank
Dialogue: 0,0:59:39.92,0:59:42.76,Default,,0000,0000,0000,,Caroline for her marvelous talk. {\i1}Applause,{\i0} {\i1}final music{\i0}
Dialogue: 0,0:59:42.76,1:00:13.00,Default,,0000,0000,0000,,subtitles created by c3subtitles.de\Nin the year 2019. Join, and help us!