A5043500732- Ion-surface interactions and analysis
- Advanced Chemical Physics Studies
- Integrated Circuits and Semiconductor Failure Analysis
- Near-Field Optical Microscopy
- Diamond and Carbon-based Materials Research
- Spectroscopy and Quantum Chemical Studies
- Atomic and Molecular Physics
- Semiconductor materials and devices
- Force Microscopy Techniques and Applications
- Laser-induced spectroscopy and plasma
- Silicon Nanostructures and Photoluminescence
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor Quantum Structures and Devices
- Thin-Film Transistor Technologies
- Electronic and Structural Properties of Oxides
- Laser Material Processing Techniques
- Silicon and Solar Cell Technologies
- Luminescence Properties of Advanced Materials
- Quantum, superfluid, helium dynamics
- Nuclear Physics and Applications
- Photonic and Optical Devices
- Glass properties and applications
- Cold Atom Physics and Bose-Einstein Condensates
- Ultrasonics and Acoustic Wave Propagation
- Quantum Dots Synthesis And Properties
Vanderbilt University
2012-2024
Tennessee State University
2018
Japan Advanced Institute of Science and Technology
2012
University of Notre Dame
2010
Fisk University
2007
University of Minnesota
2006
Oak Ridge National Laboratory
1976-2006
University of Tennessee at Knoxville
2006
Honeywell (United States)
2003
Honeywell Federal Manufacturing and Technologies (United States)
2003
The optical response of semiconducting monolayer transition-metal dichalcogenides (TMDCs) is dominated by strongly bound excitons that are stable even at room temperature. However, substrate-related effects such as screening and disorder in currently available specimens mask many anticipated physical phenomena limit device applications TMDCs. Here, we demonstrate these undesirable suppressed suspended devices. Extremely robust (photogain > 1,000) fast (response time < 1 ms) photoresponse...
Abstract The long‐term success of photosynthetic organisms has resulted in their global superabundance, which is sustained by widespread, continual mass‐production the integral proteins that photocatalyze chemical processes natural photosynthesis. Here, a fast, general method to assemble multilayer films composed one such photocatalytic protein complex, Photosystem I (PSI), onto variety substrates reported. resulting films, akin stacked thylakoid structures leaves, consist matrix permeable...
Detection by coincidence counting techniques of two-photon decay metastable state singly ionized helium
Low-energy ion-surface collisions have been observed to result in the emission of optical radiation arising from sputtering with simultaneous excitation. Emission functions obtained showing structure and energy thresholds which provide detailed information important understanding this newly low-energy phenomenon. These data can be understood terms excited-state efficiencies radiationless de-excitation processes compete radiative excited states sputtered atoms.
Measurements have been performed of the dependence on scattering angle and target orientation oscillatory structure recently observed in low-energy ion from surfaces. Wide variation is exhibited behavior oscillation maxima as a function depending species studied. A semiquantitative model presented which treats phenomenon terms quantum mechanical phase interference between pairs near-resonant quasimolecular levels.
Ultrafast time-resolved differential reflectivity of Bi2Se3 crystals is studied using optical pump-probe spectroscopy. Three distinct relaxation processes are found to contribute the initial transient changes. The deduced timescale and sign change suggest that electron–phonon interactions defect-induced charge trapping underlying mechanisms for three processes. After crystal exposed air, relative strength these altered becomes strongly dependent on excitation photon energy.
Failure of conventional adiabatic criterion in case excitation helium atoms by ions
Direct evidence for a size effect in self-trapped exciton (STE) photoluminescence (PL) from silica-based nanoscale materials as compared with bulk type-III fused silica is obtained. Two kinds of mesostructures were tested: (1) nanoparticle composites primary particle 7 and 15 nm, (2) ordered disordered mesoporous silicas pore ranging \ensuremath{\sim}2 to \ensuremath{\sim}6 nm wall thickness \ensuremath{\sim}1 nm. The PL was induced by the two-photon absorption focused 6.4 eV ArF laser light...
Abstract Low energy heavy particle bombardment of solid surfaces is observed to be accompanied by the emission infrared, visible and ultraviolet radiation. Line radiation arising from transitions between discrete atomic or molecular levels may attributed decay sputtered backscattered excited particles which have escaped surface. Broadband continuum also in low-energy collisions with arises surface appears a strictly state phenomenon. Measurement collision induced optical constitutes powerful...
Received 18 October 1965DOI:https://doi.org/10.1103/PhysRevLett.15.815©1965 American Physical Society
The lifetime of the stretch mode bond-center hydrogen in crystalline silicon is measured to be T1 = 7.8+/-0.2 ps with time-resolved, transient bleaching spectroscopy. low-temperature spectral width absorption line due converges towards its natural for decreasing concentration C(H), and nearly coincides C(H) approximately 1 ppm. lifetimes Si-H modes selected hydrogen-related defects are estimated from their widths shown range 1.6 more than 37 ps.
Fully angular-resolved kinetic-energy distributions of alkali and halogen atoms emitted due to electron-stimulated desorption have been measured for (100) (110) alkali-halide surfaces. An unexpected strong directional emission nonthermal along the 〈100〉 axis investigated crystals has found which is in contradiction predictions previously proposed ``Pooley model.'' We propose a new model involving diffusion hot holes surface, sudden localization excited hole at surface crystal.
Past efforts to achieve selective bond scission by vibrational excitation have been thwarted energy thermalization. Here we report resonant photodesorption of hydrogen from a Si(111) surface using tunable infrared radiation. The wavelength dependence the desorption yield peaks at 0.26 electron volt: Si-H stretch mode. is quadratic in intensity. A strong H/D isotope effect rules out thermal mechanisms, and electronic effects are not applicable this low-energy regime. molecular mechanism...
The first observation of atomic line radiation due to the photon-stimulated desorption excited neutral atoms is reported. Synchrotron incident on alkali-halide surfaces found result in a surprisingly high yield desorbed alkali atoms, more than three orders magnitude larger ions. Marked structure incident-photon-energy-dependent ${\mathrm{Li}}^{*}$ resonance intensity suggests that induced by secondary electronic processes.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIn situ spectrochemical analysis of solid surfaces by ion beam sputteringN. H. Tolk, I. S. T. Tsong, and C. W. WhiteCite this: Anal. Chem. 1977, 49, 1, 16A–30APublication Date (Print):January 1977Publication History Published online21 September 2008Published inissue 1 January 1977https://doi.org/10.1021/ac50009a001RIGHTS & PERMISSIONSArticle Views60Altmetric-Citations59LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum full text...
Pronounced elliptic polarization has been observed in Balmer radiation following low-energy grazing-incidence collisions of ${\mathrm{H}}^{\ensuremath{-}}$, ${\mathrm{H}}^{+}$, ${\mathrm{H}}_{2}^{+}$, and ${\mathrm{H}}_{3}^{+}$ on a clean lead surface maintained under ultrahigh vacuum. The polarization, shown to arise predominantly from $p$ states, is found depend only velocity, not the charge or molecular species incoming projectile. A two-step surface-interaction model presented based...
Recent experiments have shown that during the irradiation of lithium fluoride crystals by a chopped electron beam signal desorbed ground-state atoms continues for times up to seconds in beam-off period. A quantitative model is presented which connects desorption with diffusion F centers surface. The thus introduces new source time delay (F-center diffusion) metal from alkali halides. Formerly it has been supposed occurred entirely surface step. fits experimental data very well, and should be...
We report first studies of long-lived oscillations in optical pump-probe measurements on GaSb-GaAs heterostructures. The arise from a photogenerated coherent longitudinal acoustic phonon wave, which travels the top surface GaSb across interface into GaAs substrate, providing information properties material as function time/depth. Wavelength-dependent near bandgap indicate strong correlations to GaAs.
Electron-surface collisions have been observed to result in the emission of optical radiation from desorbed atoms and molecules. The first resonance lines Na Li alkali-halide targets, Balmer hydrogen, OH molecular are among detected. These observations discrete line originating adsorbed particles ejected surface due electron-stimulated desorption.
Pronounced oscillatory structure and strong optical polarization effects have been observed in emission cross sections for the production of radiation measured as a function energy low-energy (100 eV to 6 keV) ${\mathrm{Na}}^{+}$-Ne atomic collisions. Highly regular found dependence ten $\mathrm{NeI}(3p\ensuremath{\rightarrow}3s)$ transitions is be antiphase with similar two $\mathrm{NaI}(3p\ensuremath{\rightarrow}3s)$ sections. In addition, large from excited $J\ensuremath{\ne}0$ states....
Measurements of the O-H and O-D vibrational lifetimes show that room-temperature hydrogen diffusion rate in rutile TiO2 can be enhanced by 9 orders magnitude when stimulated resonant infrared light. We find local oscillatory motion proton quickly couples to a wag-mode-assisted classical transfer process along c channel with jump greater than 1 THz barrier height 0.2 eV. This increase transport at moderate temperatures provides new insight into solids, which could play role applications...