A5064077110- Advanced Chemical Physics Studies
- Atomic and Molecular Physics
- Mass Spectrometry Techniques and Applications
- Advanced Electron Microscopy Techniques and Applications
- Electron and X-Ray Spectroscopy Techniques
- Spectroscopy and Quantum Chemical Studies
- Quantum, superfluid, helium dynamics
- Ion-surface interactions and analysis
- Advanced X-ray Imaging Techniques
- Laser-Matter Interactions and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Photochemistry and Electron Transfer Studies
- Electrochemical Analysis and Applications
- Quantum Mechanics and Applications
- Photosynthetic Processes and Mechanisms
- Pulsed Power Technology Applications
- Advanced Fluorescence Microscopy Techniques
- Photocathodes and Microchannel Plates
- Advanced Semiconductor Detectors and Materials
- Chemical Reactions and Mechanisms
- Force Microscopy Techniques and Applications
- Pediatric Urology and Nephrology Studies
- Particle Accelerators and Free-Electron Lasers
Okinawa Institute of Science and Technology Graduate University
2017-2022
Okinawa Prefecture
2018-2019
Lawrence Berkeley National Laboratory
2005-2016
University of California, Davis
2009-2011
Goethe University Frankfurt
2007
Donostia International Physics Center
2007
Material Physics Center
2007
Saint Petersburg State University of Aerospace and Instrumentation
2007
Kansas State University
2007
The wave nature of particles is rarely observed, in part because their very short de Broglie wavelengths most situations. However, even with close to the size surroundings, couple environment (for example, by gravity, Coulomb interaction, or thermal radiation). These couplings shift phases, often an uncontrolled way, and resulting decoherence, loss phase integrity, thought be a main cause transition from quantum classical behavior. How much interaction needed induce this transition? Here we...
We investigate single-photon double ionization of ${\mathrm{H}}_{2}$ by 130 to 240 eV circularly polarized photons. find a slitlike interference pattern in the sum momentum both electrons molecular frame which survives integration over all other degrees freedom. The difference and individual electron distributions do not show such robust pattern. that this results from non-Heitler-London fraction ground state where are at same atomic center.
Momentum imaging experiments on dissociative electron attachment (DEA) to a water molecule are combined with ab initio theoretical calculations of the angular dependence quantum mechanical amplitude for provide detailed picture molecular dynamics dissociation via two lowest energy Feshbach resonances. The combination momentum and theory can reveal which axial recoil approximation breaks down thus provides powerful reaction microscope DEA polyatomics.
A joint experimental and theoretical study on dissociative electron attachment to ammonia molecules has identified Feshbach states responsible for the two principal breakup channels observed decades ago. The insight obtained reveals rich collisional dynamics that lead a breakdown of axial recoil approximation mirror images angular distributions in channels.
We investigate photo-double-ionization of ${\mathrm{H}}_{2}$ by circular polarized photons at $h\ensuremath{\nu}=160\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The previously observed two-center interference pattern in the angular distribution electron sum momentum is shown to depend strongly on internuclear distance and summed momenta.
Momentum imaging experiments on dissociative electron attachment (DEA) to CO2 are combined with the results of ab initio calculations provide a detailed and consistent picture dissociation dynamics through 8.2 eV resonance, which is major channel for DEA in CO2. The present study resolves several puzzling misconceptions about this system.
We have used cold target recoil ion momentum spectroscopy to study the continuum correlation between photoelectron of core-photoionized neon and subsequent Auger electron. observe a strong angular two electrons. Classical trajectory Monte Carlo calculations agree quite well with energy distribution that is shifted due potential change associated decay. However, striking discrepancy results in relative angle photoelectron. The classical model predicts shift flux away from emission direction,...
We describe an experimental approach to image the three-dimensional (3D) momentum distribution of negative ions arising from dissociative electron attachment (DEA). The apparatus employs a low energy pulsed gun, effusive gas source and 4π solid-angle ion imaging spectrometer consisting extraction field, electrostatic lens, time- position-sensitive detector. time-of-flight impact position each are measured event by in order full 3D sphere. system performance is tested measuring anion...
A combined experimental and theoretical investigation of the dissociative-electron-attachment (DEA) dynamics in methanol are presented for Feshbach resonance at 6.5-eV incident electron energy. Highly differential laboratory-frame momentum distributions have been measured each fragmentation channel using a DEA reaction microscope. These measurements with calculations molecular-frame attachment probability order to investigate dissociating transient negative anion. In contrast previous...
Following prior work on the lower-energy resonances, we apply techniques of momentum imaging and ab initio scattering calculations to process dissociative electron attachment water via highest-energy ${}^{2}{B}_{2}$ resonance. We focus H${}^{\ensuremath{-}}$ anion fragment, which is produced dynamics passing through avoiding conical intersection with lower ${A}_{1}$ state, leading OH (${}^{2}\ensuremath{\Pi}$) (${}^{2}\ensuremath{\Sigma}$), respectively. The technique, when combined...
We present a combined experimental and theoretical investigation of the dynamics angular dependence dissociative electron attachment to methane. show that triply degenerate (T2) Feshbach resonance is responsible for broad 10 eV dissociation peak in This alone shown correlate asymptotically various channels observed experimentally. The molecular-frame entrance amplitude calculated each component threefold resonance. By investigating topology anion potential energy surfaces, we deduce main...
With a femtosecond laser pulse we rapidly ionize potassium atoms $({\mathrm{K}}^{0})$ in the gas phase, generating ions $({\mathrm{K}}^{+})$, and monitor altered energy-level scheme with subsequent hard x-ray pulse. Removal of $4s$ valence electron increases binding energies both $1s$ core levels, induces an ultrafast change $1s\text{\ensuremath{-}}4p$ transition energy by about $2.8\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. We simultaneously observe 50% increase oscillator strength...
A Reply to the Comment by N. Bhargava Ram, Vaibhav S. Prabhudesai, and E. Krishnakumar.Received 15 December 2010DOI:https://doi.org/10.1103/PhysRevLett.106.049302© 2011 American Physical Society
We have performed open cell transmission electron microscopy experiments through pure water vapor in the saturation pressure regime (>0.6 kPa), a modern microscope capable of sub-Å resolution. systematically studied achievable levels, stability and gas purity, effective thickness column associated scattering processes, effect on optical resolution image contrast. For example, for 1.3 kPa 300kV electrons, we report ± 20 Pa over tens minutes, 0.57 inelastic mean free paths, lattice 0.14 nm...
The dynamics of the dissociative electron attachment(DEA)to water via first resonances, 2B1, is investigated by using a modified Coltrims spectrometer for imaging dissociation dynamics. channel H- ion found to be + OH(2Π), and negative ions are observed ejected out perpendicular incident direction, which agree with previously reported measurements. For O- ion, however, yields an order magnitude smaller than what have been in literature.
In the collision of electrons with molecules and molecular ions, excitation dissociation are dominated by resonant processes, where electron becomes temporarily trapped, changing forces felt nuclei. We have carried out calculations on process leading to dissociative attachment recombination. separate problem into two steps. First, resonance parameters obtained from accurate scattering using Complex Kohn variational method. Then these used as input dynamics calculations. will illustrate...
The scanning transmission electron microscopy (STEM) mode of today's field emission microscopes enables sub-nanometer resolution imaging. Graphene is a single-atom thick, electrically conductive material, making it an excellent specimen support for the low voltage STEM imaging nanometer-sized objects such as viruses. Here we present images bacteriophage T4 recorded on highly cleaned graphene films. results show that ultrathin films markedly improve image signal at accelerating voltages....
We have measured the charge-state distributions of argon and potassium after ionization by photons with energies near $K$-shell threshold. Despite similarity in core electron configurations, two atoms show remarkable differences resulting distribution ion charge states. The valence is rarely a spectator during relaxation, its presence enhances loss electrons excited into Rydberg levels or strongly reduces recapture slow photoelectrons postcollision interaction.
We report the results of our combined experimental and theoretical investigation on dynamics dissociative electron attachment to triatomic molecule CO2. The experiments employ a 4π momentum spectrometer collect kinematically complete data for this 2-body dissociation reaction. angular dependence entrance amplitudes, calculated by ab initio methods, connect laboratory frame molecular frame. Preliminary from ongoing investigations DEA larger molecules, including formic acid nucleobases uracil...
The mean free path governing the scattering of high-energy electrons in cadmium telluride (CdTe) has been measured and analyzed using off-axis electron holography (OEH). In first part study, total value was determined via acquisition aggregation a large dataset at 300 kV room temperature, yielding λOEH=52±7 nm. This is significantly shorter than some previously reported values obtained different experimental techniques theoretical calculations. To confirm validity measurement to understand...
The dynamics of the dissociative electron attachment(DEA)to water(H2O, D2O)via three resonances, 2B1, 2A1, 2B2, are investigated using modified Coltrims spectrometer. angular dependence negative ion shows unique distribution in each resonance indicating resonances involve different dissociation dynamics. energy among fragments considerable amount body break.