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Full-Text Articles in Physical Sciences and Mathematics
Mutual Ionization In 200-Kev H⁻+ He Collisions, T. Ferger, Daniel Fischer, Michael Schulz, R. Moshammer, A. B. Voitkiv, B. Najjari, J. Ullrich
Mutual Ionization In 200-Kev H⁻+ He Collisions, T. Ferger, Daniel Fischer, Michael Schulz, R. Moshammer, A. B. Voitkiv, B. Najjari, J. Ullrich
Physics Faculty Research & Creative Works
We studied mutual ionization in 200-keV H-+He collisions in a kinematically complete experiment by measuring the fully momentum-analyzed recoil ions and both active electrons in coincidence. Comparison of the data to our calculations, based on various theoretical models, show that mutual ionization proceeds predominantly through the interaction between both electrons. The post-collision interaction between the outgoing ejected electrons as well as higher order processes involving the interaction between the core of both collision partners are also important.
Kinetic, Spectroscopic, And X-Ray Crystallographic Characterization Of The Functional E151h Aminopeptidase From Aeromonas Proteolytica, Krzysztof P. Bzymek, Aaron Moulin, Sabina I. Swierczek, Dagmar Ringe, Gregory A. Petsko, Brian Bennett, Richard C. Holz
Kinetic, Spectroscopic, And X-Ray Crystallographic Characterization Of The Functional E151h Aminopeptidase From Aeromonas Proteolytica, Krzysztof P. Bzymek, Aaron Moulin, Sabina I. Swierczek, Dagmar Ringe, Gregory A. Petsko, Brian Bennett, Richard C. Holz
Physics Faculty Research and Publications
Glutamate151 (E151) has been shown to be catalytically essential for the aminopeptidase from Vibrio proteolyticus (AAP). E151 acts as the general acid/base during the catalytic mechanism of peptide hydrolysis. However, a glutamate residue is not the only residue capable of functioning as a general acid/base during catalysis for dinuclear metallohydrolases. Recent crystallographic characterization of the d-aminopeptidase from Bacillus subtilis (DppA) revealed a histidine residue that resides in an identical position to E151 in AAP. Because the active-site ligands for DppA and AAP are identical, AAP has been used as a model enzyme to understand the mechanistic role of H115 in …
Signature Of Chaos In High-Lying Doubly Excited States Of The Helium Atom, Anh-Thu Le, Toru Morishita, X.-M. Tong, C. D. Lin
Signature Of Chaos In High-Lying Doubly Excited States Of The Helium Atom, Anh-Thu Le, Toru Morishita, X.-M. Tong, C. D. Lin
Physics Faculty Research & Creative Works
We examined nearest-neighbor spacing (NNS) statistics in doubly excited states of helium near the double ionization threshold. Using the Brody parameter q to measure the NNS distribution between the regular Poisson distribution (q=0) and the chaotic Wigner distribution (q=1), we showed that for levels near the N=20 threshold of He⁺, or at about 0.13eV below the double ionization threshold, the NNS distribution has q=0.66. The result shows the slow approach of the NNS of helium energy levels towards the Wigner distribution vs the excitation energy. Using an s-wave model where the angular momentum of each electron is restricted to zero, …