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Full-Text Articles in Physics

H2s Adsorption On Chromium, Chromia, And Gold/Chromia Surfaces: Photoemission Studies, J A. Rodriguez, S Chaturvedi, U Diebold, M Kuhn, J Van Ek, P S. Robbert, H Geisler, C A. Ventrice Jr Jan 1997

H2s Adsorption On Chromium, Chromia, And Gold/Chromia Surfaces: Photoemission Studies, J A. Rodriguez, S Chaturvedi, U Diebold, M Kuhn, J Van Ek, P S. Robbert, H Geisler, C A. Ventrice Jr

Physics Faculty Publications

The reaction of H2S with chromium, chromia, and Au/chromia films grown on a Pt(111) crystal has been investigated using synchrotron-based high-resolution photoemission spectroscopy. At 300 K, H2S completely decomposes on polycrystalline chromium producing a chemisorbed layer of S that attenuates the Cr 3d valence features. No evidence was found for the formation of CrSx species. The dissociation of H2S on Cr3O4 and Cr2O3 films at room temperature produces a decrease of 0.3–0.8 eV in the work function of the surface and significant binding-energy shifts (0.2–0.6 eV) …


Intrinsic Chaos In A Dc Field Biased Quantum Heterostructure, A. Jason Mcnary, Ashok Puri Jan 1997

Intrinsic Chaos In A Dc Field Biased Quantum Heterostructure, A. Jason Mcnary, Ashok Puri

Physics Faculty Publications

A closed, quantum, double barrier, GaAs/AlGaAs heterostructure is made chaotic by adding a nonlinear potential term, αQ(t)〉, to the time-dependent Schrödinger equation, and the dynamical behavior of an electron cloud moving in the heterostructure biased by a dc electric field is examined numerically. Using phase-space diagrams, power spectrums, and Lyapunov exponents, both qualitative and quantitative measures of the chaos in the system were taken. In general, for all values of α, the nonlinearity parameter, the Lyapunov exponent, λ, increases as the applied dc field, β, increases. However, for values of α ⩽ 1.376, we notice …


Optical Studies Of Ge Islanding On Si(111), P. D. Persans, P. W. Deelman, K. L. Stokes, L. J. Schowalter, A. Byrne, T. Thundat Jan 1997

Optical Studies Of Ge Islanding On Si(111), P. D. Persans, P. W. Deelman, K. L. Stokes, L. J. Schowalter, A. Byrne, T. Thundat

Physics Faculty Publications

We report an experimental study of the optical properties of island layers resulting from molecular beam epitaxial deposition of Ge on Si(111) substrates. The combination of electroreflectance spectroscopy of the E1 transition and Raman scattering allows us to separately determine the strain and composition of the islands. For deposition at 500 °C a deposited layer of 1.36 nm of Ge assembles into 80 nm diameter islands 11 nm thick. The average Si impurity content in the islands is 2.5% while the average in-plane strain is 0.5%. Both strain and Si impurity content in islands decrease with increasing Ge deposition