UP 2020 - Invited Speakers

DATE: 4/17/2019

Time-resolved spectroscopy with multiple synchronized mode-locked lasers
Minhaeng Cho
IBS Center for Molecular Spectroscopy and Dynamics, Korea
Abstract: How atoms and electrons in a molecule move during a chemical reaction and how rapidly energy is transferred to or from the surroundings can be studied with flashes of laser light. However, despite prolonged efforts to develop various coherent multidimensional spectroscopic techniques, the lack of an all-encompassing method capable of both femtosecond time resolution and wide dynamic range measurement has hampered various applications of studying correlated electron dynamics in functional materials and biological systems. Recently, there have been a few attempts to develop linear and nonlinear optical spectroscopic techniques with two phase-stabilized mode-locked lasers called optical frequency combs. Over the past two years, we showed that dual frequency comb-based linear absorption, transient absorption, and time- and frequency-resolved transient refraction and absorption measurements of optical chromophores in solutions could be experimentally feasible. In particular, we have demonstrated that broadband synchronized mode-locked lasers enable transient pump-probe and two-dimensional electronic spectroscopy of condensed phases to measure both high-resolution coherent vibrational spectrum and nanosecond electronic relaxation.
 
Biography: Minhaeng Cho is the director of the IBS Center for Molecular Spectroscopy and Dynamics, established in Dec. 2014 and Professor of Chemistry at Korea University, Seoul, Korea, since 1996. He grew up in Seoul, where he attended the public schools. He received his B.S. and M.S. from Seoul National University in 1987 and 1989, respectively, before studying in U.S. A. where he received his Ph.D. in 1993 from the University of Chicago. He returned to Korea in 1996 as an Assistant Professor at the Korea University after a two-year post-doctoral research experience at MIT, Cambridge, USA. He became a full Professor at the Korea University in 2003 before his directorship with IBS in 2014. IBS Center for Molecular Spectroscopy and Dynamics (CMSD), located in the Seoul campus of Korea University, emphasizes developments of novel time- and space-resolved spectroscopy techniques and their applications to chemically reactive and biologically important systems. He is a member of Korean Academy of Science and Technology (KAST) and received numerous awards given by American Chemical Society, National Science Foundation in Korea, KAST, Kyung-Am Science Foundation, and National Academy of Science in Korea.
Multidimensional photoemsission spectroscopy of excitons
Ralph Ernstorfer
Fritz Haber Institute, Germany
Abstract: TBA
 
Biography: TBA
Tracking ultrafast transport of photoexcitations at the nanoscale
Naomi Ginsberg
University of California, Berkeley, USA
Abstract: The ability of energy carriers to move between atoms and molecules underlies biochemical and material function. Understanding and controlling energy flow, however, requires observing it on ultrasmall and ultrafast spatiotemporal scales, where energetic and structural roadblocks dictate the fate of energy carriers. I will describe a newly developed non-invasive stroboscopic optical scheme that leverages non-resonant interferometric scattering to track tiny changes in material polarizability created by a wide range of energy carriers. This approach, stroboSCAT, thus allows us to map evolving energy carrier distributions in four dimensions of spacetime with few-nanometer lateral precision and direct correlation to material morphology. We visualize exciton, charge, heat, sound, and ion transport in a wide variety of new and old semiconductors, conductors, and prototypical battery materials to elucidate how disorder affects energy flow in 3D. For example, we show that morphological boundaries in polycrystalline metal halide perovskites possess lateral- and depth-dependent resistivities, blocking lateral transport for surface but not bulk carriers. We furthermore reveal strategies to interpret energy transport in disordered environments that will direct the design of defect-tolerant functional materials of tomorrow.
 
Biography: Naomi S. Ginsberg is Associate Professor of Chemistry and Physics at University of California, Berkeley and Faculty Scientist in Materials Sciences and Molecular Biophysics and Integrated Imaging Divisions at Lawrence Berkeley National Laboratory. Since 2010 her lab elucidates electronic and molecular dynamics in soft electronic and bio materials by devising new electron and optical microscopies that characterize fast and ultrafast processes as a function of their nanoscale heterogeneities. Naomi received a B.A.Sc. in Engineering Science from University of Toronto (2000) and a Ph.D. in Physics from Harvard University (2007), and then held a Seaborg Postdoctoral Fellowship at LBNL. She previously observed initiating ultrafast events of photosynthesis and slowed, stopped, and stored light pulses in some of the coldest atom clouds on Earth. She is Berkeley lead of STROBE, a NSF imaging science center, a member of the Berkeley Kavli Energy NanoSciences Institute, and recipient of a David and Lucile Packard Fellowship (2011), DARPA Young Faculty Award (2012), Alfred P. Sloan Foundation Fellowship (2015), Camille Dreyfus Teacher-Scholar Award (2016), Miller Professorship for Basic Science at UC Berkeley (2017-18), and Kroto Lectureship in Chemical Physics (2019) in addition to a set of teaching awards.
 
THz-induced strongly nonlinear phenomena
Keith Nelson
Massachusetts Institute of Technology, USA
Abstract: TBA
 
Biography: TBA
Ultrafast time-resolved protein crystallography – recent insights
Ilme Schlichting
Max-Planck Institute for Medical Research, Germany
Abstract: Light is important for organisms from all domains of life, serving as an energy resource or carrier of information initiating intra- or intercellular signaling. Photosensitive proteins, endowed with a light-absorbing chromophore, enable this. Detailed insight into the ultrafast events has been obtained by various forms of spectroscopy and computation. However, direct structural information necessary to understand the underlying molecular mechanisms has been inaccessible until recently. The femtosecond X-ray pulses provided by X-ray free-electron lasers allow acquisition of high-resolution diffraction data from micron-sized macromolecular crystals at room temperature beyond the limitations of radiation damage imposed by conventional X-ray sources. Moreover, the short duration of the pulses enable time-resolved studies at the chemical time-scale of femtoseconds. Therefore the unique properties of X-ray free electron lasers open the sub-ps time domain for time-resolved crystallography using small crystals that can be efficiently photolyzed, thus providing access to the long sought-after excited state and intermediate structures. This is not only important for the fundamental understanding of light-driven processes but has practical impact on future developments of e.g. fluorescent proteins for optical nanoscopy or retinal proteins for optogenetics. We present recent insight on the initial events in photodissociation and isomerization reactions obtained by time-resolved serial femtosecond crystallography experiments.
 
Biography: Ilme Schlichting heads the Department of Biomolecular Mechanisms at the Max Planck Institute for Medical Research in Heidelberg. She studied biology and physics at Heidelberg University. After obtaining her Ph.D. with Kenneth C. Holmes she moved to Brandeis University to postdoc with Gregory A. Petsko. Subsequently she became a group leader in Roger Goody’s department at the Max Planck Institute of Molecular Physiology in Dortmund before accepting her position as a director at the MPI in 2002. Schlichting’s research aims at understanding how proteins achieve their unique functional properties. Her group studies mainly heme and flavin containing proteins. Both cofactors allow for a plethora of different reactions, yet, most of the enzymes are highly specific catalysts. Thus, an important question is how does the protein fine-tune the reactivity of the cofactor and of the intermediates occurring during the reaction? Key insight is obtained from structures of reaction intermediates. Schlichting was the first to successfully combine photolysis of caged compounds and Laue crystallography to study GTP hydrolysis by the Ras protein, to observe ligand binding intermediates in myoglobin, and to resolve the reaction intermediates of a cytochrome P450 at high spatial resolution. Her latest interests include the application of X-ray Free Electron Laser radiation for structural biology.
Light-wave driven charge- and spin dynamics
Martin Schultze
University of Technology Graz, Austria
Abstract: Ultrafast coherent electron and spin dynamics in solids In electronics, functionality is achieved by switching between electronic states of matter by applying external electric or magnetic fields. Strong couplings in-between charge carriers and to the crystal lattice conspire to randomize energies and momenta extremely fast and efficiently, leaving little room for coherent manipulation. However, the prospects of coherent control protocols as demonstrated in isolated atomic systems are alluring and contemporary ultrafast laser sources might be a new ingredient to overcome this entrapment. This talk will discuss two experiments demonstrating that single cycle optical fields at optical frequencies allow manipulating electronic and spin degrees of freedom in solid state systems at optical clock rates faster than de-coherence. Ultrafast bidirectional energy transfer between a light-field and the band-structure of silica proves the early times reversibility of electronic excitations and holds promise of novel ultrafast, coherent optoelectronic applications1. As a corollary of this ultrafast coherent modification of the electronic system, in suitably chosen herterostructures also the spin system can be manipulated coherently. Optically induced spin transfer is demonstrated as a route to the direct, all-optical manipulation of macroscopic magnetic moments on previously inaccessible attosecond timescales2. 1. Sommer, A. et al. Attosecond nonlinear polarization and light–matter energy transfer in solids. Nature 534, 86–90 (2016). 2. Siegrist, F. et al. Light-wave dynamic control of magnetism. Nature 571, 240–244 (2019).
 
Biography: PhD on Delay in Photoemission at LMU Munich, Germany. Postdoc at Max-Planck Institute of Quantum Optics, Germany and the UC Berkely, USA on attosecond spectroscopy in condensed phase systems. Since 2019 professor of physics and head of the institute of experimental physics at the Technical University Graz, Austria. Research activities centered around the exploration of ultrafast light-wave manipulation of electronic and spin degrees of freedom in solid-state systems.
High-energy mid-infrared femtosecond pulses for attosecond science
Eiji J. Takahashi
RIKEN, Japan
Abstract: Since the first demonstration of isolated attosecond pulses in 2001, attosecond science has emerged as an important frontier research area of ultrafast phenomena. However, one critical bottleneck in the progress of research studying attosecond phenomena is the limited pulse energy of attosecond pulses. In this talk, I will introduce our two novel laser systems to drive high-energy attosecond pulses: one is 50-mJ 3-channel waveform synthesizer consisting of pulses with near-infrared and mid-infrared wavelengths, and the other is a multi-TW mid-infrared laser system via dual-chirped optical parametric amplification (DC-OPA).
 
Biography: Eiji J. Takahashi is a Senior Research Scientist at RIKEN Center for Advanced Photonics. After receiving his Ph.D degree in 2001, he contributed to the early development of intense high-order harmonic sources and spectroscopy in RIKEN. In 2004, he joined the Institute for Molecular Science, Okazaki, Japan, where he was an Assistant Professor. Since re-joining RIKEN in 2006, he is a member of the Attosecond Science Research Team. Currently, he is mainly focusing on the energy scaling of isolated attosecond pulses up to gigawatt-scale and the development high-energy MIR laser system based on DC-OPA. His research interests include high-intensity laser-matter interactions, the generation of coherent soft-x-ray/XUV pulses, attosecond science, and high-power laser technology including an optical waveform synthesizer.
Ultrafast dynamics of molecules in strong laser fields
Jian Wu
East China Normal University, China
Abstract: We experimentally investigate the ultrafast dynamics of molecules in strong laser fields by measuring the ejected electrons and nuclear fragments in coincidence, revealing the electron-nuclear partition of the absorbed multiphoton energy and the consequent ultrafast dynamics of the electron and nuclear wave packets.
 
Biography: Wu Jian, Professor of the State Key Laboratory of Precision Spectroscopy, East China Normal University (ECNU). He received his B.S. and Ph.D. degrees from ECNU. He was appointed as an Associated Professor at ECNU in 2007 and promoted to be a full Professor in 2010. With a grant from the Alexander von Humboldt Foundation, he carried out his postdoctoral research at the Goethe University Frankfurt. He was selected as the Distinguished Young Scholars of NSFC (2014), Ten-thousand Talents Program (2019), National Youth Top-notch Talents (2015), the New Century Excellent Talents in University (2013), and the Eastern Scholar of Shanghai Municipal Education Commission (2013). He was invited to serve as the International Advisory Board of the Journal of Physics B (Royal Society of Physics), and the Topic Editor of Chinese Optics Letters. His research focuses on the measurement and control of the ultrafast dynamics of molecules in strong laser fields. He has published more than 100 papers in peer-reviewed journals, including 1 Nature Physics, 21 PRL, 1 PNAS, 1 PRX, and 5 Nature Communications.
Spintronic Terahertz Emission with Manipulated Polarization
Xiaojun Wu
Beihang University, China
Abstract: Laser terahertz emission spectroscopy is a powerful tool not only for investigating ultrafast light-matter interaction phenomenon but also for developing terahertz emission materials for next-generation novel terahertz sources. Terahertz emitters especially polarization tunable sources play a significant role in terahertz science and applications such as terahertz wireless communication, biological effects, and fundamental physics. However, up to now, there are not many terahertz sources with flexibly controlled and manipulated polarization functions. In this talk, I will introduce several kinds of nanomaterials including magnetic nanofilms and topological insulators, on which we can realize arbitrary terahertz polarizations. Such kind of polarization integrated terahertz sources are based on spin not charge property of electron, which not only provide us a new freedom to further understand fundamental science of ultrafast opto-spintronics but also open a new way to accelerating the development twisting the terahertz light at the on-chip terahertz sources.
 
Biography: Prof. Xiaojun Wu got her Ph.D degree in the Institute of Physics, Chinese Academy of Science in 2013. During August 2013 to July 2014, she was a postdoctor in Hamburg University. From August 2014-April 2017, she was awarded the Alexander von Humboldt Fellowship. In May 2017, she joined in Beihang University and started a terahertz research group. She has published >80 academic papers including Nature Photonics, Nature Communications, Optica, Advanced Optical Materials and so on. She has give >20 keynote and invited talks, and holds 10 patents. She is the Co-chair of POEM-TSA, international technical program committee of CLEO-TST, MTSA, Asia-Photonics and so on. She participates in more than ten projects from National Natural Science Foundation of China (NSFC) and Beijing National Natural Science Foundation (BNSF). Her research interests include Generation of Strong-field terahertz radiation and its nonlinear phenomena, smart terahertz sensing and imaging, and on-chip terahertz photonics.
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Conference Date:

July 19-24, 2020

Important Dates:

Paper Submission Deadline:

Jan. 31, 2020

Mar. 1, 2020

Early Bird Registration Deadline:

Jun. 19, 2020

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