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Title: Charge transfer and electronic excitation in collisions of protons with water molecules below 10 keV

Abstract

Charge transfer and electronic excitation processes for H{sup +}+H{sub 2}O collisions are investigated theoretically below 10 keV. Molecular-orbital close-coupling approach is employed for scattering dynamics, while an ab initio multireference single- and double-configuration interaction method is used for the determination of molecular states. The present results for charge transfer show rather weak energy dependence in the energy range from 10 keV down to a few tens of eV with very slowly varying cross-section value of 4-13x10{sup -16} cm{sup 2}, and are found to be in excellent agreement with experimental measurements by Lindsay et al. [Phys. Rev. A 55, 3945 (1997)] where the energy in the experiment and theory overlaps. The electronic-excitation cross sections are found to be much smaller than those for the charge transfer, but increase rapidly and become comparable to charge transfer at a few keV. Most of the water molecular ions and excited species produced in the collision are unstable and soon undergo dissociation; some insight into the fragmentation process and the fragmented species is given.

Authors:
; ; ; ; ; ;  [1];  [2];  [3]
  1. Graduate School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan)
  2. (Japan)
  3. (Germany)
Publication Date:
OSTI Identifier:
20982120
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.75.022706; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; CHARGE EXCHANGE; CONFIGURATION INTERACTION; COUPLING; CROSS SECTIONS; DISSOCIATION; ENERGY DEPENDENCE; EXCITATION; FRAGMENTATION; HYDROGEN IONS 1 MINUS; ION-MOLECULE COLLISIONS; KEV RANGE 01-10; MOLECULAR IONS; MOLECULAR ORBITAL METHOD; MOLECULES; PROTONS; SCATTERING; WATER

Citation Formats

Mada, Shogo, Hida, Ken-nosuke, Kimura, Mineo, Pichl, Lukas, Liebermann, Heinz-Peter, Li, Yan, Buenker, Robert J., Division of Natural Sciences, International Christian University, Osawa 3-10-2, Mitaka, Tokyo 181-8585, and Fachbereich C-Mathematik und Naturwissenschaften, Bergische Universitaet Wuppertal, D-42119 Wuppertal. Charge transfer and electronic excitation in collisions of protons with water molecules below 10 keV. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.022706.
Mada, Shogo, Hida, Ken-nosuke, Kimura, Mineo, Pichl, Lukas, Liebermann, Heinz-Peter, Li, Yan, Buenker, Robert J., Division of Natural Sciences, International Christian University, Osawa 3-10-2, Mitaka, Tokyo 181-8585, & Fachbereich C-Mathematik und Naturwissenschaften, Bergische Universitaet Wuppertal, D-42119 Wuppertal. Charge transfer and electronic excitation in collisions of protons with water molecules below 10 keV. United States. doi:10.1103/PHYSREVA.75.022706.
Mada, Shogo, Hida, Ken-nosuke, Kimura, Mineo, Pichl, Lukas, Liebermann, Heinz-Peter, Li, Yan, Buenker, Robert J., Division of Natural Sciences, International Christian University, Osawa 3-10-2, Mitaka, Tokyo 181-8585, and Fachbereich C-Mathematik und Naturwissenschaften, Bergische Universitaet Wuppertal, D-42119 Wuppertal. Thu . "Charge transfer and electronic excitation in collisions of protons with water molecules below 10 keV". United States. doi:10.1103/PHYSREVA.75.022706.
@article{osti_20982120,
title = {Charge transfer and electronic excitation in collisions of protons with water molecules below 10 keV},
author = {Mada, Shogo and Hida, Ken-nosuke and Kimura, Mineo and Pichl, Lukas and Liebermann, Heinz-Peter and Li, Yan and Buenker, Robert J. and Division of Natural Sciences, International Christian University, Osawa 3-10-2, Mitaka, Tokyo 181-8585 and Fachbereich C-Mathematik und Naturwissenschaften, Bergische Universitaet Wuppertal, D-42119 Wuppertal},
abstractNote = {Charge transfer and electronic excitation processes for H{sup +}+H{sub 2}O collisions are investigated theoretically below 10 keV. Molecular-orbital close-coupling approach is employed for scattering dynamics, while an ab initio multireference single- and double-configuration interaction method is used for the determination of molecular states. The present results for charge transfer show rather weak energy dependence in the energy range from 10 keV down to a few tens of eV with very slowly varying cross-section value of 4-13x10{sup -16} cm{sup 2}, and are found to be in excellent agreement with experimental measurements by Lindsay et al. [Phys. Rev. A 55, 3945 (1997)] where the energy in the experiment and theory overlaps. The electronic-excitation cross sections are found to be much smaller than those for the charge transfer, but increase rapidly and become comparable to charge transfer at a few keV. Most of the water molecular ions and excited species produced in the collision are unstable and soon undergo dissociation; some insight into the fragmentation process and the fragmented species is given.},
doi = {10.1103/PHYSREVA.75.022706},
journal = {Physical Review. A},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • Charge-transfer processes in collisions of H{sup +} and O{sup +} ions with C{sub 2}H{sub 4} molecules have been studied in joint theoretical and experimental approaches for collision energies below 10 keV/u. Since H and O atoms possess nearly identical ionization potentials, these two ions are expected to share similar dynamics and hence to have similar cross-section values for charge transfer, at least for the energy region above 100 eV. In the present experiments, these cross sections of H{sup +} and O{sup +} ions have been derived by the initial growth rate method in the energy range of 0.20 to 3.6more » keV, while the present theoretical study has been carried out for H{sup +} impact only. We have examined the vibrational effect on charge transfer, especially the 'temperature effect' of the initial vibrational states of the C{sub 2}H{sub 4} molecule as well as the final vibrational states of the product C{sub 2}H{sub 4}{sup +} molecular ion. Indeed, a strong influence of the initial vibrational states on charge transfer has been observed since these vibrationally excited initial and final states force the process to be more nearly resonant, thus making charge transfer more efficient. This vibrational effect, and perhaps rotational effect as well, that makes the collision process more nearly resonant has not been well investigated previously, and thus the present study is expected to shed much light on this effect in general.« less
  • Single- and double-charge-transfer cross sections of {sup 3}He{sup 2+} ions in collisions with N{sub 2}, O{sub 2}, CO, and CO{sub 2} molecules have been measured in the energy range of 0.20 to 2.7 keV/u. In addition, the same type of measurements for H{sub 2} molecules has been also carried out again for energies in the range from 0.13 to 0.40 keV/u. For all molecules except for CO{sub 2}, the present single-charge-transfer cross sections are found to be generally larger than, or at least comparable to, double-charge-transfer cross sections in the energy region studied. This is a marked difference in comparisonmore » to experimental results reported earlier where a sharp increase for double charge transfer was observed below 0.3 keV/u. The double-charge-transfer cross sections are found to be apparently larger than single-charge-transfer cross sections only for CO{sub 2} molecules at energies below 0.8 keV/u. A theoretical analysis based on a close-coupling method within a molecular representation has also been carried out for H{sub 2} and CO targets to provide some insights.« less
  • Electron capture and excitation in O[sup +]([sup 4][ital S],[sup 2][ital D],[sup 2][ital P])+He collisions above 100 eV are studied theoretically by using a semiclassical molecular representation and electron capture in He[sup +]+O([sup 3][ital P]) collisions; excitation and deexcitation in O[sup +]([sup 4][ital S])+He[leftrightarrow]O[sup +]([sup 2][ital D])+He collisions at lower energies are studied by using a fully-quantum-mechanical molecular representation. At higher energies, nonadiabatic couplings are the driving forces that cause transitions. At collision energies below 10 eV, transitions are driven by spin-orbit couplings. At kilo-electron-volt energies, the contribution from metastable O[sup +]([sup 2][ital D],[sup 2][ital P]) ions to electron capture ismore » much larger than that from the ground O[sup +]([sup 4][ital S]) ions. At energies below 1 eV, the cross section for electron capture in He[sup +]+O collisions is very small, with a magnitude of less than 10[sup [minus]20] cm[sup 2]. The cross sections for the excitation-deexcitation of metastable O[sup +] ions are larger, with values near 10[sup [minus]18] cm[sup 2].« less
  • Charge transfer in B{sup 2+}({sup 2}{ital S},{sup 2}{ital P})+He and in B{sup 3+}({sup 1}{ital S})+He collisions is studied theoretically by using a semiclassical molecular representation with 8 and 12 molecular channels for B{sup 2+} and B{sup 3+} on He systems, respectively, at collision energies between 200 eV and 200 keV for the former and between 600 eV and 50 keV for the latter. The {ital ab} {ital initio} potential curves and nonadiabatic coupling matrix elements are obtained from the multireference single- and double-excitation configuration-interaction (MRD-CI) calculations for the B{sup 2+}-He system and a pseudopotential-modified configuration-interaction method for the B{sup 3+}-Hemore » system. The present cross sections for charge transfer by the ground state B{sup 2+} ions are found to have a broad maximum with a magnitude as large as 2{times}10{sup {minus}15} cm{sup 2} at 100 keV and those by an excited B{sup 2+}({sup 2}{ital P}) state are found to be larger by a factor of 6 than those by the ground state in the same energy regime. B{sup 2+}-excitation cross sections are smaller than those for charge transfer below 1 keV, while they increasingly dominate above this energy. The present total charge-transfer cross section for B{sup 3+} in collisions with He is similar to that obtained in earlier work by Gargaud {ital et} {ital al}. [J. Phys. B {bold 27}, 3985 (1994)] both in magnitude and energy dependence, but is found to show slightly different B{sup 2+}(2{ital s}) and B{sup 2+}(2{ital p}) production ratio. {copyright} {ital 1996 The American Physical Society.}« less
  • Previous calculations of ion-atom interactions by the pseudopotential and asymptotic methods are used in the computation of the cross section for symmetric charge transfer at energies below 1 keV. The results for Li/sup +/, Na/sup +/, K/sup +/, Rb/sup +/, Cs/sup +/, and Ca/sup +/ ions are compared with data obtained in beam experiments, and by optical-pumping techniques. The difference in the cross sections for /sup 2/P/sub 1///sub 2/ and /sup 2/P/sub 3///sub 2/ ions of Kr/sup +/ and Xe/sup +/ at thermal energies is studied, and the predictions are compared with recent mobility measurements. Cross sections are obtained formore » U/sup +/-U collisions, and the dependence of the thermal cross section on the polarizability is described. Symmetric charge transfer of the negative ions H/sup -/, Na/sup -/, and Cs/sup -/ is discussed briefly. (AIP)« less