Charge transfer processes in ion-molecule collisions at intermediate energies; the vibrational effect, isotope effect, isomer effect, and steric effect

M. Kimura1), L. Pichl2), H. Suno3), R. Suzuki4), R. J. Buenker5), Y. Li5), P. Libermann5), T. Kusakabe6)

(1) Graduate School of Sciences, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
(2) Department of Computer SW, University of Aizu, Aizu-Wakamatsu 965-8580, Japan
(3) National Institue for Fusion Science, Toki, Gifu 509-5292, Japan
(4) Computer Center, Hitotsubashi University, Tokyo 186-8603, Japan
(5) Theoretische Chemie, Bergische Universitaet-Gesamthoscschule Wuppertal, D-42097 Wuppertal, Germany
(6) Department of Science, Kinki University, Higashi-Osaka, Osaka, 577-8502 Japan

Among many interactions and dynamical processes, charge transfer processes of slow H+ ions in collisions with H2, H2O, CO, CO2, and hydrocarbon molecules are some of the most fundamental and important ion-molecule collisions in basic sciences and applications. They are of vital importance not only that this collision process provides the fundamental knowledge of underlying collision physics, but also that it is far more important in numerous applications such as plasma, material, medical and astrophysical sciences. In the research of the controlled thermonuclear fusion, these collisions play a key role in low temperature edge plasmas of the current fusion devices [1].
From a few hundred eV to above in collision energy, customarily, it has long been ignored in treating the vibrationally excited-target explicitly in ion-molecule collisions in general because vibrational energy levels are much smaller compared to the relative collision energy of keV. However, recently, the importance of the vibrational effect on charge transfer and ionization in ion-molecule collisions has been pointed out experimentally and theoretically [2, 3], and enhancement of charge transfer cross sections by a few order of magnitude from vibrationally excited molecular-target in keV collision energy region has been shown. In addition, we have also examined the isotope effect between H2 and D2, isomer effect among hydrocarbons and steric effect, and these observations will be fully discussed.

References

[1] R. K. Janev, in Atomic and Molecular Processes in Fusion Edge Plasmas, edited by R. K. Janev, (Plenum, New York, 1995), pp.1-13.
[2] T. Kusakabe, S. Satoh, H. Tawara and M. Kimura, Phys. Rev. Lett. 87, 243201 (2001).
[3] T. Kusakabe, K. Asahina, J. P. Gu, G. Hirsch, R. J. Buenker, M.Kimura, H. Tawara, and Y. Nakai, Phys. Rev. A 62, 062714 (2000).