Biomedical subjects

J A Yarmoff

Publications and source records attributed to J A Yarmoff.

4 recordsLinked to original sources

PubMed2006

Li ion scattering from Au nanoclusters on TiO2(110).

The neutralization of low energy 7Li+ scattered from Au nanoclusters deposited on TiO2(110) was measured with time-of-flight spectroscopy as a function of cluster size, emission angle, and ion energy. The neutralization shows maxima for cluster diameters approximately 3 nm, and again for thick Au films. The data are compared to previous experiments with Na projectiles. Possible explanations of the observed effects are discussed.

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PubMed2004

Detection of quantum confined states in au nanoclusters by alkali ion scattering.

Charge state-resolved time-of-flight spectra were collected for 2.0 keV 23Na+ scattered from Au nanoclusters deposited on TiO2(110). The neutral fraction of Na scattered from metallic Au is low ( approximately 3%), but it is surprisingly high (up to 50%) for small clusters. The results demonstrate that alkali ions couple to electronic states specific to the nanoclusters, and that the energy of the states is a function of the nanocluster size. This technique provides a new method for the spectroscopy of nanomaterials.

Journal Article↗

PubMed2002

Charge exchange in Li scattering from Si surfaces.

Neutral fractions are measured for 4 keV 7Li(+) scattering from clean, hydrogen-covered, and cesiated Si surfaces. The neutral fraction in scattering from clean Si is approximately 26% and it decreases with hydrogen adsorption. When Cs is adsorbed on Si, the neutral fraction does not distinguish the local potential at the Cs sites from the Si sites, unless hydrogen is coadsorbed. These results demonstrate that resonant charge transfer occurs due to coupling of the Li ionization level with the dangling bond surface states, and that the influence of the dangling bonds extends beyond the local scattering sites.

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PubMed2001

Surface-reconstruction-switched adsorbate photofragmentation dynamics.

Energy-resolved angular distributions of neutral fragments ejected during photoinduced electron transfer reaction of CH3Br on GaAs(100) exhibit three distinct methyl-radical ejection channels. These undergo marked changes when the termination is switched from the Ga-rich c(8 x 2) to the As-rich c(2 x 8). Our observations are consistent with a strong adsorption-site dependence of the dynamics.

Journal Article↗