Theoretical Study of Resonance Phenomena in Electron-Capture Processes by Multiply-Charged Ions from Alkali-Metal Atoms.

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Resonance phenomena are expected to appear in electron capture processes by multiply-charged ions from neutral atoms at very low collision energies, but the observation has not yet been succeeded until now. In order to find out the collision systems in which the resonance phenomena appear at collision energy as high as possible and to make clear the mechanism for the resonance phenomena, we performed the calculations of the cross sections for electron capture with quantum mechanical close-coupling method in collisions of He^<2+>,Be^<2+>,Be^<4+>,B^<3+>,B^<5+>,C^<2+>,C^<4+>,C^<6+>,N^<2+>,N^<3+>,N^<5+>,N^<7+>,Li^+,Li^<2+>,Li^<3+> ions with alkali-metal atoms. As the results the collision energies at which peaks appear and the width of the peaks were elucidated for these collision systems. The dependence of the resonance-position on target atoms, incident ions, and charges were also investigated. Furthermore, the eigenvalues and eigenfunctions for resonance states were obtained by spectral method. The dynamics of resonance were investigated by multi-channel wave-packet method and the visualization of the resonance phenomena was succeeded.In general, the resonances appear at higher collision energy for the system in which the target atoms have large polarizability and incident ions have higher charge. However, we must call attention for the occurrence of the repulsion of potential curves. Our calculated results show that in the (He^<2+> + Li,Na) collision systems the resonances appear at most high collision energy (about 0.3 eV).Because the potential well due to bond-formation is much deep than that due to polarization, we calculated the cross sections for the (H^+ + H) collision system in laser field considering only the lowest Σ_g and Σ_u states. The calculated results show that resonances appear at very high collision energy (about 2 eV).