A5082486292- Ion-surface interactions and analysis
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor materials and devices
- Integrated Circuits and Semiconductor Failure Analysis
- Atomic and Molecular Physics
- Mass Spectrometry Techniques and Applications
- Astro and Planetary Science
- Diamond and Carbon-based Materials Research
- Surface and Thin Film Phenomena
- Analytical Chemistry and Sensors
- Semiconductor materials and interfaces
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Laser-induced spectroscopy and plasma
- Theoretical and Computational Physics
- Physics of Superconductivity and Magnetism
- Radiation Effects in Electronics
- Nuclear Physics and Applications
- Advanced Materials Characterization Techniques
- Stellar, planetary, and galactic studies
- Atomic and Subatomic Physics Research
- Plasma Diagnostics and Applications
- High-pressure geophysics and materials
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum, superfluid, helium dynamics
Clemson University
2013-2023
Cornell University
1999-2004
National Institute of Standards and Technology
2003
We report on a measurement of craters in thin dielectric films formed by Xe(Q+) (26 ≤ Q 44) projectiles. Tunnel junction devices with ion-irradiated barriers were used to amplify the effect charge-dependent cratering through exponential dependence tunneling conductance barrier thickness. Electrical crater σ(c)(Q) increased 4 orders magnitude (7.9 × 10(-4) μS 6.1 μS) as increased, corresponding depths ranging from 2 11 Å. By employing heated spike model, we determine that energy required...
The predictions of nonlocal London theory are confirmed by real-space measurements the hexagonal-to-square transition in vortex lattice structure ${\mathrm{V}}_{3}\mathrm{Si}.$ We observe that transforms from hexagonal to nearly square over field range 0--4 T for fields applied along [001] direction. Above $\ensuremath{\approx}0.75\mathrm{T},$ we find orientation is strongly linked symmetry underlying ${\mathrm{V}}_{3}\mathrm{Si}$ crystal and has a (100) plane. Near rhombus-to-square at 4 T,...
We have performed measurements of the spatial distribution current in various alkali and reactive ion beams over energy range 5–600 eV using a Faraday cup. Ion beam densities been extracted from these simple deconvolution procedure. Our results reveal that are Gaussian shape with constant width, σ, for energies greater than approximately 75 all species investigated. This width is consistent determined oxygen on Cu(001) crystal after an O+ deposition, measured Auger electron spectroscopy....
Polycarbonate targets were irradiated with multicharged ions of argon and oxygen kinetic energies between 375 eV 1 keV. Scanning electron microscopy (SEM) x-ray photoelectron spectroscopy (XPS) analysis following the irradiations showed evidence bond-breaking at polycarbonate surface. The extent ion-induced damage indicates that ion charge state enhances well beyond observed for similar, low flux singly charged ions. A qualitative comparison a simple description radius capture initial...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation R. Shyam, D. Kulkarni, A. Field, E. S. Srinadhu, B. Cutshall, W. Harrell, J. Harriss, C. Sosolik; First multicharged ion irradiation results from the CUEBIT facility at Clemson University. AIP Conf. Proc. 9 January 2015; 1640 (1): 129–135. https://doi.org/10.1063/1.4905410 Download citation file: Ris (Zotero)...
An ultrahigh vacuum ion beamline and chamber have been assembled to produce hyperthermal (<400 eV) energy ions for studying hot electron chemistry at surfaces. The specific design requirements this modified instrument were chosen enable the exposure of a metal-oxide-semiconductor (MOS) device monoenergtic, well-collimated beams alkali while monitoring both scattered beam flux characteristics. Our goal is explore role that electrons injected toward MOS surface play in neutralization ions. To...
We report on a measurement of low energy ion irradiation effects as-grown films SiO2 Si substrate. Beams normally incident Na <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ions with kinetic energies 2 keV to 5 were focused onto ~ 1900 Å films. Aluminum top metal contacts subsequently deposited these targets such that irradiated regions and unexposed (pristine) the target could be compared using capacitance-voltage (C-V) measurements...
We apply the classical over-the-barrier (COB) model to charge transfer between highly charged ions (HCIs) and targets consisting of thin dielectric films on metals. Distances for onset classically allowed above-surface electron capture are obtained as a function HCI state, film thickness, permittivity, film-metal binding energies. The describes crossover previously existing COB bulk metals dielectrics thickness metal substrate increases through three distinct regimes. For ultrathin with low...
The recent detection of a neutron star merger by the LIGO collaboration has renewed interest in laboratory studies r-process elements. Accurate modeling and interpretation electromagnetic transients following mergers requires computationally expensive calculations both structure opacity all trans-iron To date, necessary atomic data to benchmark codes are incomplete or, some cases, absent entirely. Within available studies, literature on Au i ii provides reports emission lines level...
Neutralization probabilities are presented for hyperthermal energy Na+ ions scattered from a Cu(001) crystal as function of surface temperature and velocity. A large enhancement in neutralization is observed the increased. Velocity-dependent charge transfer regimes probed by varying incident energy, with most prominent effects occurring at lowest energies. The data agree well results obtained model based on Newns-Anderson Hamiltonian, where both velocity incorporated.
Extensive experimental and theoretical results are presented for the scattering of a beam ${\mathrm{K}}^{+}$ ions incident on Cu(001) surface along ⟨100⟩ azimuth with energies $50\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}154\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. Energy-resolved scattered intensity spectra reveal three distinct peaks whose widths intensities vary temperature. Using classical trajectory simulation, four ionic types assigned to these peaks. mechanical...
Oxygen ion and neutral atom yields were measured for ${\mathrm{O}}^{+}$ ${\mathrm{O}}^{\ensuremath{-}}$ ions incident on a clean Cu(001) surface energies from 0.4 to 5 keV. Scattering geometries chosen that simplify the selection of single collisions between atoms consequently also identification charge transfer mechanisms occurring in O-Cu system. It was found ratio is independent state, demonstrating memory loss occurs over entire range scattering investigated. From general arguments based...
We investigate internal hot carrier excitations in a Au thin film bombarded by hyperthermal and low energy alkali noble gas ions. Excitations within the of metal-oxide-semiconductor device are measured revealing that ions whose velocities fall below classical threshold given free-electron model metal still excite carriers. Excellent agreement between these results nonadiabatic accounts for time-varying ion-surface interaction indicates due to semilocalized electrons near surface.
We have made Na (+) and He ions incident on the surface of solid state tunnel junctions measured energy loss due to atomic displacement electronic excitations. Each junction consists an ultrathin film metal-oxide-semiconductor device which can be biased create a band hot electrons useful for driving chemical reactions at surfaces. Using binary collision approximation nonadiabatic model that takes into account time-varying nature ion-surface interaction, is reproduced. The devices shows...
Direct detection of gravitational waves (GWs) on 17 August 2017, propagating from a binary neutron star merger, or “kilonova”, opened the era multimessenger astronomy. The ejected material mergers, is good candidate for optical and near infrared follow-up observations after GWs. kilonova ejecta GW1780817 provided first evidence astrophysical site synthesis heavy nuclei through rapid capture process r-process. Since properties emission are largely affected by opacities material, enhancements...
A gas cell apparatus to measure charge exchange cross sections for state- and energy-resolved ion beams with neutrals is described. The design features a short well-defined interaction region required of multicharged ions high sections. Our method includes measuring the beam transmission at four different neutral pressures extracting section from slope loss vs pressure plot. procedure were tested Ar+ interacting Ar over incident energy range 1.0-5.0 keV. agree well previous complementary...
Thanks to high-resolution and non-dispersive spectrometers onboard future X-ray missions such as XRISM Athena, we are finally poised answer important questions about the formation evolution of galaxies large-scale structure. However, currently lack an adequate understanding many atomic processes behind spectral features will soon observe. Large error bars on parameters critical transition energies cross sections can lead unacceptable uncertainties in calculations e.g., elemental abundance,...
In this paper we report the first observation of x-ray radiation from new Clemson University Electron Beam Ion Trap (CUEBIT). The analysis emitted dielectronic recombination photons highly charged argon ions allowed us to probe parameters specific ion cloud inside machine. Argon resonances could provide a standard method cross-compare electron beam and characteristics different devices.