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Full-Text Articles in Physics

Fragmentation Processes Following Core Excitation In Acetylene And Ethylene By Partial Ion Yield Spectroscopy, Maria Novella Piancastelli, Wayne C. Stolte, Gunnar Ohrwall, S-W Yu, D. Bull, K. Lantz, Alfred S. Schlachter, Dennis W. Lindle Nov 2002

Fragmentation Processes Following Core Excitation In Acetylene And Ethylene By Partial Ion Yield Spectroscopy, Maria Novella Piancastelli, Wayne C. Stolte, Gunnar Ohrwall, S-W Yu, D. Bull, K. Lantz, Alfred S. Schlachter, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

Partial ion yield spectroscopy provides a very detailed picture of fragmentation processes following core excitation in isolated molecules. We exploit this potential in the analysis of decay processes following C1s→π and C1s→Rydberg excitations in ethylene and acetylene. We show that the relative intensity of spectral features related to the excitation to empty molecular orbitals or to Rydberg states is a function of the time variation of the fragmentation process. Namely, we see an intensity increase in the Rydberg states compared to the molecular orbitals as the fragmentation process becomes more extensive, a result attributable to the diffuse nature of the …


Holographic Analysis Of Diffraction Structure Factors, S. Marchesini, N. Mannella, C. S. Fadley, M. A. Van Hove, J. J. Bucher, D. K. Shuh, L. Fabris, M. J. Press, M. W. West, Wayne C. Stolte, Z. Hussain Sep 2002

Holographic Analysis Of Diffraction Structure Factors, S. Marchesini, N. Mannella, C. S. Fadley, M. A. Van Hove, J. J. Bucher, D. K. Shuh, L. Fabris, M. J. Press, M. W. West, Wayne C. Stolte, Z. Hussain

Chemistry and Biochemistry Faculty Research

We combine the theory of inside-source/inside-detector x-ray fluorescence holography and Kossel lines/x ray standing waves in kinematic approximation to directly obtain the phases of the diffraction structure factors. The influence of Kossel lines and standing waves on holography is also discussed. We obtain partial phase determination from experimental data obtaining the sign of the real part of the structure factor for several reciprocal lattice vectors of a vanadium crystal.


In-Situ X-Ray-Absorption Spectroscopy Study Of Hydrogen Absorption By Nickel-Magnesium Thin Films, B. Farangis, Ponnusamy Nachimuthu, T. J. Richardson, J. L. Slack, Rupert C. Perera, Eric M. Gullikson, Dennis W. Lindle, M. Rubin Jul 2002

In-Situ X-Ray-Absorption Spectroscopy Study Of Hydrogen Absorption By Nickel-Magnesium Thin Films, B. Farangis, Ponnusamy Nachimuthu, T. J. Richardson, J. L. Slack, Rupert C. Perera, Eric M. Gullikson, Dennis W. Lindle, M. Rubin

Chemistry and Biochemistry Faculty Research

Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in-situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Co-deposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied …


Correlated Alternative Side Chain Conformations In The Rna-Recognition Motif Of Heterogeneous Nuclear Ribonucleoprotein A1, Jacqueline Vitali, Jianzhong Ding, Jianzhong Jiang, Ying Zhang, Adrian R. Krainer, Rui-Ming Xu Apr 2002

Correlated Alternative Side Chain Conformations In The Rna-Recognition Motif Of Heterogeneous Nuclear Ribonucleoprotein A1, Jacqueline Vitali, Jianzhong Ding, Jianzhong Jiang, Ying Zhang, Adrian R. Krainer, Rui-Ming Xu

Physics Faculty Publications

The RNA-recognition motif (RRM) is a common and evolutionarily conserved RNA-binding module. Crystallographic and solution structural studies have shown that RRMs adopt a compact α/β structure, in which four antiparallel β-strands form the major RNA—binding surface. Conserved aromatic residues in the RRM are located on the surface of the β-sheet and are important for RNA binding. To further our understanding of the structural basis of RRM—nucleic acid interaction, we carried out a high resolution analysis of UP1, the N-terminal, two-RRM domain of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), whose structure was previously solved at 1.75–1.9 Å …


Effects Of Nonequilibrium Atmospheric Pressure Plasmas On The Heterotrophic Pathways Of Bacteria And On Their Cell Morphology, Mounir Laroussi, J. Paul Richardson, Fred C. Dobbs Jan 2002

Effects Of Nonequilibrium Atmospheric Pressure Plasmas On The Heterotrophic Pathways Of Bacteria And On Their Cell Morphology, Mounir Laroussi, J. Paul Richardson, Fred C. Dobbs

OES Faculty Publications

To date, most research on the interaction of nonequilibrium, atmospheric pressure plasma discharges with bacteria has concentrated on the germicidal effects. Therefore, published results deal mainly with killing efficacy and little attention is given to physical mechanisms and biochemical pathways and their potential alterations when cells of microorganisms are exposed to the plasma. In this letter, an attempt to investigate the effects of plasma exposure on the biochemical pathways of bacteria is presented. In addition, using electron microscopy, we investigate if any gross morphological changes take place when cells are exposed to a lethal dose of plasma. We are testing …