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

多电荷离子在极低碰撞能量下从中性原子中俘获电子的过程中可能会出现共振现象，但迄今为止还没有成功的观测到这一现象。为了寻找在尽可能高的碰撞能量下出现共振现象的碰撞体系，并弄清共振现象的机理，我们用量子力学密耦方法计算了He^<2+>，Be^<2 +>，Be^<4+>，B^<3+>，B^<5+>，C^<2+>，C^<4+>碰撞中的电子俘获截面，具有碱金属原子的C^<6+>、N^<2+>、N^<3+>、N^<5+>、N^<7+>、Li^+、Li^<2+>、Li^<3+>离子。作为结果，阐明了这些碰撞系统的峰出现的碰撞能量和峰的宽度。共振位置对靶原子，入射离子和电荷的依赖关系也进行了研究。进而用谱方法得到了共振态的本征值和本征函数。用多通道波包方法研究了共振动力学，并成功地可视化了共振现象，一般情况下，当靶原子极化率大，入射离子带电荷高时，共振出现在较高的碰撞能量处.然而，我们必须注意势曲线的斥力的出现。计算结果表明，在（He^<2+> + Li，Na）碰撞体系中，共振出现在最高碰撞能量（约0.3eV）处，由于成键势阱比极化势阱深得多，因此我们只考虑了（H^+ + H）碰撞体系的最低激发态和最低激发态，计算了（H^+ + H）碰撞体系在激光场中的散射截面.计算结果表明，共振出现在很高的碰撞能量（约2 eV）。

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).