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Publications (In-House Listing)

Axis-dependence of molecular high harmonic emission in three dimensions - 2014 - High-order harmonic generation in an atomic or molecular gas is a promising source of sub-femtosecond vacuum ultraviolet coherent radiation for transient scattering, absorption, metrology and imaging applications. High harmonic spectra are sensitive to Ångstrom-scale structure and motion of laser-driven molecules, but interference from radiation produced by random molecular orientations obscures...
X-ray pump/X-ray probe femtosecond coherent diffractive imaging of electron dynamics in pristine and embedded xenon clusters - 2014 - Femtosecond time-resolved coherent diffractive imaging (CDI) experiments on pristine Xe clusters and Xe clusters embedded in superfluid helium nanodroplets have been performed using a new undulator-based X-ray pump/X-ray probe technique at the Linac Coherent Light Source (LCLS). The study aims at elucidating electron dynamics in sub-micron sized clusters induced by irradiation...
High Harmonic mixing in Solid Argon - Georges Ndabashimiye, Shambhu Ghimire , David Reis 2014 - We measure high harmonics of 800 nm and 1333 nm fundamental radiation in thin solid argon films. The thickness dependence of the above gap harmonics shows evidence for nonlinear mixing between low and high orders. In particular the thickness dependences show similar length scales suggesting that they originate from the...
Towards jitter-free time resolved measurements at Xray Free Electron Lasers - Gilles Doumy, Chris Roedig, Kai-Kai Zhang, Pierre Agostini, Lou DiMauro, Adrian Cavalieri, Ivanka Grguras, Michael Meyer, John Costello, Wolfram Helml , Reinhard Kienberger, Christoph Bostedt , Sebastian Schorb, Ryan Coffee 2014 - The advent of X-ray Free Electron Lasers (XFEL) has quickly revolutionized the field of time resolved x-ray techniques. The availability of tunable pulses ranging from the soft to the hard x-ray region, and lasting only few tens of femtoseconds is enabling access to unprecedented temporal resolution using classic pump-probe techniques....
Determination of the neon double core hole lifetime using high-intensity x-rays from the LCLS - EP Kanter, G Doumy, AM March, SH Southworth, L Young, JD Bozek, C Bostedt, M Messerschmidt Publication date 2014/6/3 2014 - The concentration of x-ray photons in a focussed radiation pulse at the SLAC Linac Coherent Light Source (LCLS) exposes atoms to multiple sequential photoabsorption processes [1]. For ∼keV x rays the absorption in neon targets primarily the 1s shell and hollow neon atoms are readily created when the rate of...
Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers - Johan Hattne, Nathaniel Echols, Rosalie Tran, Jan Kern, Richard J Gildea, Aaron S Brewster, Roberto Alonso-Mori, Carina Glöckner, Julia Hellmich, Hartawan Laksmono , Raymond G Sierra, Benedikt Lassalle-Kaiser, Alyssa Lampe, Guangye Han, Sheraz Gul, Dörte DiFiore, Despina Milathianaki, Alan R Fry, Alan Miahnahri, William E White, Donald W Schafer, M Marvin Seibert, Jason E Koglin, Dimosthenis Sokaras, Tsu-Chien Weng, Jonas Sellberg, Matthew J Latimer, Pieter Glatzel, Petrus H Zwart, Ralf W Grosse-Kunstleve, Michael J Bogan, Marc Messerschmidt, Garth J Williams, Sébastien Boutet, Johannes Messinger, Athina Zouni, Junko Yano, Uwe Bergmann, Vittal K Yachandra, Paul D Adams, Nicholas K Sauter 2014 - X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the...
Toward atomic resolution diffractive imaging of isolated molecules with x-ray free-electron lasers - Stephan Stern , Lotte Holmegaard, Frank Filsinger, Arnaud Rouzée, Artem Rudenko, Per Johnsson, Andrew V Martin, Anton Barty, Christoph Bostedt , John D Bozek, Ryan N Coffee, Sascha Epp, Benjamin Erk, Lutz Foucar, Robert Hartmann, Nils Kimmel, Kai-Uwe Kühnel, Jochen Maurer, Marc Messerschmidt, Benedikt Rudek, Dmitri G Starodub, Jan Thøgersen, Georg Weidenspointne, Thomas A White, Henrik Stapelfeldt, Daniel Rolles, Henry N Chapman, Jochen Küpper 2014 - We give a detailed account of the theoretical analysis and the experimental results of an x-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Coherent Light Source [Phys. Rev. Lett. 112, 083002 (2014)]. This experiment is the...
Real-time visualization of nanocrystal solid-solid transformation pathways - Joshua Wittenberg, Timothy Miller, Elizabeth Szilagyi, Katherine Lutker, Florian Quirin, Wei Lu, Henrik T Lemke, Diling Zhu, Matthieu Chollet, Joseph Robinson, Haidan Wen, Klaus SOKOLOWKI-TINTEN, A Paul Alivisatos, Aaron Lindenberg 2014 - Measurement and understanding of the microscopic pathways materials follow as they transform is crucial for the design and synthesis of new metastable phases of matter. Here we employ femtosecond single-shot X-ray diffraction techniques to measure the pathways underlying solid–solid phase transitions in cadmium sulfide nanorods, a model system for a...
Near-Equilibrium Structural Dynamics on the 20ps Time Scale - Michael Kozina , Te Hu , Apurva Mehta, David Reis , Aaron Lindenberg 2014 - We observed near-equilibrium optically-induced structural dynamics at the Stanford Synchrotron Radiation Lightsource (SSRL). Hard x-ray diffraction experiments were performed in a typically unavailable regime: low optical pump fluence (20-250 μJ/cm2) and short x ray pulses (15-60ps). We studied several different thin films (BiFeO3 (BFO), Pb(Zr)TiO3 (PZT), and Bi), pumping above...
Acoustic Pulses in Iron Observed by Femtosecond X-ray Diffraction - Tom Henighan , Stefano Bonetti, Patrick Granitzka, Diling Zhu, Stuart Parkin, Mariano Trigo , David Reis , Herman Durr 2014 - Interest in improving the performance of memory storage devices has fueled recent discoveries in novel mechanisms for manipulating magnetic spins on ultrafast timescales, including magnetoacoustics. Direct measurement of ionic motion could allow one to observe the coupling between the magnetic spins and lattice dynamics in a crystal. In this talk,...
Exploration of Phonon Behavior in PbTe from Ultrafast Time-Resolved Pump-Probe Measurements - Mason Jiang, Matthias Hoffmann, Andrew May, Olivier Delaire, Brian Sales, Roberto Merlin, Ivana Savic, Eamonn Murray, Stephen Fahy , David Reis 2014 - We report femtosecond-resolution measurements of phonon dynamics on photo-excited PbTe, an incipient ferroelectric. PbTe is a leading thermoelectric material with an unusually low thermal conductivity, which has been attributed to strongly anharmonic phonon interactions. In an attempt to understand in detail the nature of these interactions, we perform time-resolved pump-probe...
Photon energy and carrier density dependent dynamics of the coherent A1g phonon in bismuth - Crystal Bray, Eamonn Murray, Stephen Fahy , David Reis 2014 - We investigate the dynamics of the coherent A1g phonon as a function of photon energy and carrier density for photo-excited single-crystal thin-film bismuth. Previous experimental and theoretical studies on group V semimetals such as bismuth show strong softening of the mode with photo-excitation associated with electronic softening and a reduction...
Carrier dynamics in sulfur-hyperdoped silicon studied by time-resolved terahertz spectroscopy - Meng-Ju Sher , Christie Simmons, Austin Akey, Mark Winkler, Daniel Recht, Tonio Buonassisi, Michael Aziz, Aaron Lindenberg 2014 - Intermediate-band photovoltaics have been proposed to enhance efficiencies of solar cells by harvesting additional energy from sub-bandgap photons. One proposed method for fabricating an IB material is by introducing deep-level dopants at concentrations above the insulator-to-metal transition (IMT). Theory suggests that as the dopant states become delocalized, the non-radiative recombination...
Modeling mechanophore activation within a viscous rubbery network - Meredith N Silberstein,, Lee D Cremar, Brett A Beiermann, Sharlotte B Kramer, Todd J Martinez, Scott R White, Nancy R Sottos 2014 - Mechanically induced chemical reactivity is a promising means for designing self-sensing and autonomous materials. Force sensitive chemical groups called mechanophores can be covalently linked into polymers in order to trigger specific chemical reactions upon mechanical loading. A model framework is developed to describe the response of these mechanophores to mechanical...
Systematic Improvement on the Classical Molecular Model of Water - Lee-Ping Wang, Teresa Head-Gordon, Jay Ponder, Pengyu Ren, John Chodera, Peter Eastman, Todd J Martinez, Vijay S Pande 2014 -
All-diamond optical assemblies for a beam-multiplexing X-ray monochromator at the Linac Coherent Light Source 2014 - A double-crystal diamond (111) monochromator recently implemented at the Linac Coherent Light Source (LCLS) enables splitting of the primary X-ray beam into a pink (transmitted) and a monochromatic (reflected) branch. The first monochromator crystal with a thickness of 100 um provides sufficient X-ray transmittance to enable simultaneous operation of two...
Evidence for photo-induced monoclinic metallic VO2 under high pressure - Wen-Pin Hsieh, Mariano Trigo , David A Reis, Gianluca Andrea Artioli, Lorenzo Malavasi, Wendy L Mao 2014 - We combine ultrafast pump-probe spectroscopy with a diamond-anvil cell to decouple the insulator-metal electronic transition from the lattice symmetry changing structural transition in the archetypal strongly correlated material vanadium dioxide. Coherent phonon spectroscopy enables tracking of the photo-excited phonon vibrational frequencies of the low temperature, monoclinic (M1)-insulating phase that transforms...
Angular Momentum Sensitive Two-Center Interference - M Ilchen, L Glaser, F Scholz, P Walter, S Deiner, A Rothkirch, J Seltmann, J Viefhaus, P Decleva, B Langer, A Knie, A Ehresmann, OM Al-Dossary, M Braune, G Hartmann, A Meissner, LC Tribedi, M AlKhaldi , U Becker 2014 - In quantum mechanics the Young-type double-slit experiment can be performed with electrons either traveling through a double slit or being coherently emitted from two inversion symmetric molecular sites. In the latter one the valence photoionization cross sections of homonuclear diatomic molecules were predicted to oscillate over kinetic energy almost 50 years...
Size and shape dependent photoluminescence and excited state decay rates of diamondoids - Robert Richter, David Wolter, Tobias Zimmermann, Lasse Landt, Andre Knecht, Christoph Heidrich, Andrea Merli, Otto Dopfer, Philipp Reiß, Arno Ehresmann, Jens Petersen, Jeremy E Dahl, Robert MK Carlson, Christoph Bostedt,, Thomas Möller, Roland Mitric, Torbjörn Rander 2014 - We present photoluminescence spectra and excited state decay rates of a series of diamondoids, which represent molecular structural analogues to hydrogen-passivated bulk diamond. Specific isomers of the five smallest diamondoids (adamantane–pentamantane) have been brought into the gas phase and irradiated with synchrotron radiation. All investigated compounds show intrinsic photoluminescence in...
Role of Lattice Coupling in Establishing Electronic and Magnetic Properties in Quasi-One-Dimensional Cuprates - W. S. Lee, S. Johnston, B. Moritz, J. Lee 2013 - High resolution resonant inelastic x-ray scattering has been performed to reveal the role of lattice coupling in a family of quasi-1D insulating cuprates, Ca2+5xY2-5xCu5O10. Site-dependent low-energy excitations arising from progressive emissions of a 70 meV lattice vibrational mode are resolved for the first time, providing a direct measurement of electron-lattice...
Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains - Zhenan Bao, Stefan C. B. Mannsfeld, Gi Xue, Tae Hoon Lee 2013 - Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach—termed fluid-enhanced crystal engineering (FLUENCE)—that allows for a high degree of morphological...
Selective Ultrafast Probing of Transient Hot Chemisorbed and Precursor States of CO on Ru(0001) - M. Beye, T. Anniyev, Broege Douglas, M. Dell’Angela 2013 - We have studied the femtosecond dynamics following optical laser excitation of CO adsorbed on a Ru surface by monitoring changes in the occupied and unoccupied electronic structure using ultrafast soft x-ray absorption and emission. We recently reported [M. Dell’Angela et al. Science 339 1302 (2013)] a phonon-mediated transition into a...
Tuning the Dirac Point in CVD-Grown Graphene through Solution Processed n-Type Doping with 2-(2-Methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H-benzoimidazole - Zhenan Bao, Kelly Gaffney , Peng Wei, Nan Liu, Hye Ryoung Lee, Eric Adijanto 2013 - Department of Chemical Engineering, ‡Department of Materials Science and Engineering, and §Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States San Jose Research Institute, Electronic Materials Research Center, Samsung Cheil Industries Inc., 2186 Bering Drive, San Jose, California 95131, United States Department of Physics, National University of Singapore, 2 Science...
L-Edge X-ray Absorption Spectroscopy of Dilute Systems Relevant to Metalloproteins Using an X-ray Free-Electron Laser - Mitzner, Rolf, Rehanek, Jens, Kern, Jan, Gul, Sheraz, Hattne, Johan, Taguchi, Taketo, Alonso-Mori, Roberto, Tran, Rosalie, Weniger, Christian, Schroeder, Henning, Quevedo, Wilson, Laksmono, Hartawan, Sierra, Raymond G., Han, Guangye, Lassalle-Kaiser, Benedikt, Koroidov, Sergey, Kubicek, Katharina, Schreck, Simon, Kunnus, Kristjan, Brzhezinskaya, Maria, Firsov, Alexander, Minitti, Michael P., Turner, Joshua J., Moeller, Stefan, Sauter, Nicholas K., Bogan, Michael J., Nordlund, Dennis, Schlotter, William F., Messinger, Johannes, Borovik, Andrew, Techert, Simone, de Groot, Frank M. F., Foehlisch, Alexander, Erko, Alexei, Bergmann, Uwe, Yachandra, Vittal K., Wernet, Philippe, Yano, Junko 2013 -