Ionization and single and double electron capture in proton−Ar collisions

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in The Journal of Physical Chemistry A, copyright © 2018American Chemical Society after peer review. To access the final edited and published work see http://doi.org/10.1021/acs.jpca.7b11769Total cross sections for formation of H and H–, and electron production, in H+ + Ar collisions have been calculated at energies between 100 eV and 200 keV by employing two methods: for E 10 keV, the switching-classical-trajectory-Monte Carlo method (s-CTMC). The semiclassical calculation involves transitions to molecular autoionizing states, calculated by applying a block-diagonalization technique. The s-CTMC method is adept to treat two-electron processes and yields total cross sections for H– formation in reasonably good agreement with the experimental data. Cross sections for electron- and H-production processes, which are dominated by one-electron transitions, are in good agreement with the experimental dataThis work has been partially supported by Ministerio de Economía and Competitividad (Spain), project no. ENE201452432-

Aggregation effects in proton collisions with water dimers

Charge transfer cross sections in proton collisions with water dimers are calculated using an ab initio method based on molecular orbitals of the system. Results are compared with their counterpart in proton-water collisions to gauge the importance of intermolecular interactions in the cross sectionsThis work has been supported by the project ENE2007-62934 of the Secretaría de Estado de Investigación, Desarrollo e Innovación (Spain). Allocation of computational time at the CCC of the Universidad Autónoma de Madrid is gratefully acknowledge

Near threshold rotational excitation of molecular ions by electron-impact

New cross sections for the rotational excitation of H$_3^+$ by electrons are calculated {\it ab initio} at low impact energies. The validity of the adiabatic-nuclei-rotation (ANR) approximation, combined with $R$-matrix wavefunctions, is assessed by comparison with rovibrational quantum defect theory calculations based on the treatment of Kokoouline and Greene ({\it Phys. Rev. A} {\bf 68} 012703 2003). Pure ANR excitation cross sections are shown to be accurate down to threshold, except in the presence of large oscillating Rydberg resonances. These resonances occur for transitions with $\Delta J=1$ and are caused by closed channel effects. A simple analytic formula is derived for averaging the rotational probabilities over such resonances in a 3-channel problem. In accord with the Wigner law for an attractive Coulomb field, rotational excitation cross sections are shown to be large and finite at threshold, with a significant but moderate contribution from closed channels.Comment: 3 figures, a5 page

A classical and semiclassical study of collisions between Xq+ ions and water molecules

Collisions of He2+, Li3+ and C3+ ions with water molecules are studied at energies ranging between 20 keV u-1 and 500 keV u-1. Three methods are employed: the classical trajectory Monte Carlo (CTMC), the expansion of the scattering wave function in terms of asymptotic frozen molecular orbitals (AFMO) and a lattice method to numerically solve the time-dependent Schrödinger equation (GridTDSE). Total cross sections for single ionization, single electron capture, transfer ionization and electron production are calculated and compared with previous close-coupling calculations and experiments. The fragmentation branching ratios are discussedThis work has been partially supported by Ministerio de Economía and Competitividad (Spain), project no. FIS2017-84684-

State-selective electron capture in collisions of ground and metastable N2+ ions with H(1s)

9 págs.; 12 figs.; 1 tab.; PACS number(s): 34.70.1e, 34.10.1xA calculation of the electron capture (EC) cross sections for collisions of metastable and ground states of nitrogen2+ ions with H(1s) was presented. The double translational energy spectroscopy technique facilitated the energy change spectrum in EC to be measured for an incident pure beam of ground state ions. It was found that the nuclear wave functions were derived by solving numerically the system of differential equations. It was observed that for impact energies 1 KeV, the impact parameter method was employed, where the nuclei followed straightline trajectories with constant relative velocity V and impact parameter b (R=b+vt). ©2004 The American Physical SocietyI.R. is grateful to the Spanish MCyT for a “Contrato Ramón y Cajal.” This work has been partially supported by DGICYT Projects No. BFM2000-0025 and FTN2000-0911.Peer Reviewe

Calculation of total cross section for electron capture in collisions of Carbon ions with H (D,T) (1s)

The calculations of total cross sections of electron capture in collisions of Cq+ with H (1s) are reviewed. At low collision energies new calculations have been performed using molecular expansions, to analyze isotope effects. The Classical Trajectory Monte Carlo method have been also applied to discuss the occuracy of previous calculatiosn and to extend the energy range of the available cross sectionsProject ENE2011-28200 (Secretaría de Estado de I+D+i, SPAIN

Single and double electron capture in N5+ + H2 collisions at low impact energies

8 págs.; 11 figs.; 1 tab. ; PACS number~s!: 34.70.1e, 34.10.1xCollisions of N5+ with H2 at low impact energies for single electron capture (SEC) and autonizing double electron capture (ADC) were discussed. Calculations for cross sections of SEC and ADC were carried out at impact energies between 0.1 and 10keV/amu, by applying the sudden approximation for rotation and vibration of the diatomic molecules. It was observed that sudden approximation for vibration causes discrepancy with phonon emission measurements. The results show good agreemnet with experimental data in energy range between 0.2 to 1 keV/amu for SEC into n4+ and ADC. ©2004 American Physical SocietyThis work was partially supported by DGICYT Project Nos. BFM2000-0025 and FTN2000-0911.Peer Reviewe

Classical treatment of ion-H2O collisions with a three-center model potential

We present calculations of cross sections for one- and two-electron processes in collisions of H+, He2+, and C6+ with water molecules in the framework of the Franck-Condon approximation. We employ an independent-electron method and a classical trajectory Monte Carlo approach. Anisotropy effects related to the structure of the target are explicitly incorporated by using a three-center model potential to describe the electron-H2O+ interaction. We derive scaling laws with respect to the projectile charge. We also estimate cross sections for molecular fragmentation subsequent to electron removalThis work has been partially supported by the CCG08- UAM/ESP3990 project and the DGICYT project ENE2007- 6293

A class of non-supersymmetric orientifolds

We study type IIB orientifolds on T^{2d}/Z_N with supersymmetry broken by the compactification. We determine tadpole cancellation conditions including anti-branes and considering different actions for the parity Omega. Using these conditions we then obtain the spectrum of tachyons and massless states. Various examples with N even correspond to type 0B orientifolds.Comment: 49 pages, Late

Hemiquantal treatment of low energy p+H2 collisions

We present calculations of charge exchange and vibrational excitation cross sections in low energy p+H2 collisions. These cross sections are obtained by means of an hemiquantal treatment which uses Diatomics In Molecules (DIM) diabatic wavefunctions of the H3+ molecule. The hemiquantal approach allows to distinguish the nonreactive, dissociative and nuclear exchange contributions to the electronic reaction path