Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Physics
Core-Level Spectroscopy Of The Pd/W(110) Interface: Evidence Of Long-Range Pd-Island—Winteractions At Submonolayer Coverages, D. Mark Riffe, N. D. Shinn, B. Kim, K. J. Kim, T. H. Kang
Core-Level Spectroscopy Of The Pd/W(110) Interface: Evidence Of Long-Range Pd-Island—Winteractions At Submonolayer Coverages, D. Mark Riffe, N. D. Shinn, B. Kim, K. J. Kim, T. H. Kang
All Physics Faculty Publications
We have measured W 4f7/2 core-level photoemission spectra from W(1 1 0) in the presence of Pd overlayers for coverages up to ∼1 pseudomorphic monolayer (ML). At coverages close to 0.05 ML a striking change in the W core-level spectrum is observed, which we interpret as indicating a long-range lateral effect of 2D Pd islands upon the W electronic structure in both the first and second W layers. As the coverage increases the long-range effect weakens and finally vanishes near 0.85 ML. Above this coverage the W spectra are typical for a W-based bimetallic interface, with the first-layer …
Core-Level Spectroscopy Of The Ni/W(110) Interface: Correlation Of W Interfacial Core Levelshifts With First-Layer Ni Phases, D. Mark Riffe, R. T. Franckowiak, N. D. Shinn, B. Kim, K. J. Kim, T. H. Kang
Core-Level Spectroscopy Of The Ni/W(110) Interface: Correlation Of W Interfacial Core Levelshifts With First-Layer Ni Phases, D. Mark Riffe, R. T. Franckowiak, N. D. Shinn, B. Kim, K. J. Kim, T. H. Kang
All Physics Faculty Publications
We have measured W 4f7/2 core-level photoemission spectra from W(1 1 0) in the presence of Ni overlayers, from ∼0.2 to ∼3 monolayers. Interfacial core-level shifts associated with first-layer Ni phases have been identified: −230 ± 15 meV for the 1 × 1 pseudomorphic phase and −70 ± 7 meV for the 7 × 1 close-packed commensurate phase. At higher Ni coverages the interfacial core-level shift is −100 ± 10 meV. These shifts are analyzed using the partial-shift model of Nilsson et al. [Phys. Rev. B 38 (1988) 10357]; the analysis indicates that the difference in binding energies between …
Inception Of Snapover And Gas Induced Glow Discharges, J. T. Galofaro, B. V. Vayner, D. C. Ferguson, W. A. Degroot, C. D. Thomson, John R. Dennison, R. E. Davies
Inception Of Snapover And Gas Induced Glow Discharges, J. T. Galofaro, B. V. Vayner, D. C. Ferguson, W. A. Degroot, C. D. Thomson, John R. Dennison, R. E. Davies
All Physics Faculty Publications
Ground based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant …
Nature Of Carbon-Carbon Bonding In Evaporated And Ion-Sputtered (Diamondlike) Amorphous Carbon From (E, 2e) Spectroscopy, Chao Gao, Yun Yu Wang, A. L. Ritter, John R. Dennison
Nature Of Carbon-Carbon Bonding In Evaporated And Ion-Sputtered (Diamondlike) Amorphous Carbon From (E, 2e) Spectroscopy, Chao Gao, Yun Yu Wang, A. L. Ritter, John R. Dennison
All Physics Faculty Publications
The local carbon-carbon bonding in evaporated (e-C) and ion-sputtered (i-C) amorphous carbon has been investigated by transmission electron-energy-loss spectroscopy (EELS) and by (e, 2e) spectroscopy. The EELS data indicate that the e-C is graphiclike and the i-C is diamondlike. The (e, 2e) data demonstrate that the concentration of sp2 bonding is ∼100% in both materials (0.85≤csp2≤1.0) for e-C and 0.75≤csp2≤1.0 for i-C). There is significant rehybridization of the π orbital in i-C.
Spectral Momentum Density From Graphite From Spectroscopy: Comparison With First Principles Calculations, Chao Gao, A. L. Ritter, John R. Dennison, N. A. Holzwarth
Spectral Momentum Density From Graphite From Spectroscopy: Comparison With First Principles Calculations, Chao Gao, A. L. Ritter, John R. Dennison, N. A. Holzwarth
All Physics Faculty Publications
We have measured the spectral momentum density ρ(E,q) of graphite by (e,2e) spectroscopy for momentum parallel and perpendicular to the crystal c axis. In the independent-electron approximation, ρ(E,q)=ΣG‖Uk(G)‖2 δ(q-k-G)δ(E-E(k)) where the one-electron wave function is Ψk(r)=eik⋅rΣGUk(G)eiG⋅r) and G is a reciprocal-lattice vector. The measurements covered a range of momentum parallel to the c axis equal to 0≤‖q‖≤1.84 Å-1 and a range of momentum perpendicular to the c axis equal to 0≤‖q‖≤2.35 Å-1. The energy range spanned the valence band of graphite from …
The Spectral Momentum Density Of Amorphous Carbon From (E, 2e) Spectroscopy, A. L. Ritter, John R. Dennison, R. Jones
The Spectral Momentum Density Of Amorphous Carbon From (E, 2e) Spectroscopy, A. L. Ritter, John R. Dennison, R. Jones
All Physics Faculty Publications
The spectral momentum density of the valence band of an amorphous carbon film has been measured by (e, 2e) spectroscopy. Two "bands," energy as a function of momentum, are resolved. One extends from 23 eV below the Fermi energy to about 10 eV below EF. The other, ∼ 9 eV below EF, does not disperse significantly. Although the existence of diamond bonding in the film cannot be ruled out, the bands are more suggestive of the graphite band structure.