Physical Sciences and Mathematics | Open Access Articles

Postcollision Effects In Target Ionization By Ion Impact At Large Momentum Transfer, Michael Schulz, B. Najjari, Alexander B. Voitkiv, Katharina R. Schneider, Xincheng Wang, Aaron C. Laforge, Renate Hubele, Johannes Goullon, Natalia Ferreira, Aditya H. Kelkar, Manfred Grieser, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer

Physics Faculty Research & Creative Works

We have measured and calculated fully differential cross sections for target ionization in 16-MeV O⁷⁺+He and 24-MeV O⁸⁺+Li collisions. As in previous studies, in the case of the He target we observe a pronounced forward shift in the angular distribution of the electrons relative to the direction of the momentum transfer q at small q (q < 1 a.u.). An unexpected result is that we also find a strong forward shift at large q (q > 2 a.u.), while at intermediate q this shift becomes very weak or even turns into a backward shift. For the Li target, in contrast, the forward shift monotonically increases with increasing q. These observations are qualitatively reproduced by our calculations. …

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Comment On The Ionization Energy Of B2f4, Bun Chan, Adam J. Trevitt, Stephen J. Blanksby, Leo Radom

Adam Trevitt

The Gn test sets(1) of accurate (uncertainty ≤ 1 kcal mol–1 ≈ 4 kJ mol–1) experimental data are widely employed in the development and assessment of quantum chemistry procedures. However, while all the data in the Gn sets nominally carry a sub-kcal mol–1 uncertainty, several of the experimental values show uncharacteristically large discrepancies when compared with values determined by high-level theoretical calculations. One of these questionable values is the adiabatic ionization energy (IE) of B2F4, for which the theoretical values calculated, for example, with the high-level G2 (1133.9, kJ mol–1),(1b) G3 (1135.4 kJ mol–1),(2) and G4 (1127.2 kJ mol–1)(3) procedures …

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Effect Of Protein Stabilization On Charge State Distribution In Positive- And Negative Ion Electrospray Ionization Mass Spectra, Stephen J. Watt, Margaret Sheil, Jennifer L. Beck, Pavel Prosselkov, Gottfried Otting, Nicholas E. Dixon

Professor Nick E Dixon

Changes in protein conformation are thought to alter charge state distributions observed in electrospray ionization mass spectra (ESI-MS) of proteins. In most cases, this has been demonstrated by unfolding proteins through acidification of the solution. This methodology changes the properties of the solvent so that changes in the ESI-MS charge envelopes from conformational changes are difficult to separate from the effects of changing solvent on the ionization process. A novel strategy is presented enabling comparison of ESI mass spectra of a folded and partially unfolded protein of the same amino acid sequence subjected to the same experimental protocols and conditions. …

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Polarization And Interference Effects In Ionization Of Li By Ion Impact, Renate Hubele, Aaron C. Laforge, Michael Schulz, Johannes Goullon, Xincheng Wang, B. Najjari, Natalia Ferreira, Manfred Grieser, Vitor L B D De Jesus, Robert Moshammer, Katharina R. Schneider, Alexander B. Voitkiv, Daniel Fischer

Physics Faculty Research & Creative Works

We present initial-state selective fully differential cross sections for ionization of lithium by 24 MeV O8⁺ impact. The data for ionization from the 2s and 2p states look qualitatively different from each other and from 1s ionization of He. For ionization from the 2p state, to which in our study the m_L=-1 substate predominantly contributes, we observe orientational dichroism and for 2s ionization pronounced interference which we trace back to the nodal structure of the initial-state wave function.

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Picturing Electron Capture To The Continuum In The Transfer Ionization Of Intermediate-Energy He²⁺ Collisions With Argon, Ruitian Zhang, Xinwen Ma, Shaofeng Zhang, Xiaolong Zhu, Susmitha Akula, Don H. Madison, Bingsheng Li, Dongbin Qian, Wentian Feng, Dalong Guo, Huiping Liu, Shuncheng Yan, Pengju Zhang, Shenyue Xu, Ximeng Chen

Physics Faculty Research & Creative Works

Electron emission occurring in transfer ionization for He²⁺ collisions with argon has been investigated using cold target recoil ion momentum spectroscopy. The double differential cross sections for electron capture to the continuum of the projectile (cusp-shaped electrons) are presented for collision energies from 17.5 to 75 keV/u. For an energy of 30 keV/u, we find a maximum in the experimental ratio of the cusp-shaped electron yield to the total electron yield. This result is explained in terms of the velocity matching between the projectile ion and the electron initially bound to the target. One of the important issues for …

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Ionization In Diesel Combustion For On-Board Diagnostics And Engine Control, Tamer Hassan Badawy

Wayne State University Dissertations

Diesel engines have been known for their high thermal efficiency and specific power output, but there is concern about engine-out NOx and particulate matter emissions. To meet the current emission standards, advanced diesel engines are fitted with electronically controlled fuel injection systems and sophisticated and expensive after-treatment devices. Further improvements are still needed to meet future goals in better fuel economy and the more stringent emission standards. In order to meet these goals, there is a need for the control of the combustion process to reduce engine-out emissions in real-time and reduce the demand on the after-treatment devices. This requires …

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Full-Text Articles in Physical Sciences and Mathematics

Physics Faculty Research & Creative Works

Comment On The Ionization Energy Of B2f4, Bun Chan, Adam J. Trevitt, Stephen J. Blanksby, Leo Radom

Adam Trevitt

Effect Of Protein Stabilization On Charge State Distribution In Positive- And Negative Ion Electrospray Ionization Mass Spectra, Stephen J. Watt, Margaret Sheil, Jennifer L. Beck, Pavel Prosselkov, Gottfried Otting, Nicholas E. Dixon

Professor Nick E Dixon

Physics Faculty Research & Creative Works

Physics Faculty Research & Creative Works

Ionization In Diesel Combustion For On-Board Diagnostics And Engine Control, Tamer Hassan Badawy

Wayne State University Dissertations