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

在很低的碰撞能下，中性原子的多电荷离子在电子俘获过程中有望出现共振现象，但到目前为止，这一观测尚未成功。为了尽可能地找出在碰撞能处出现共振现象的碰撞系统，并弄清共振现象产生的机制，我们用量子力学紧耦合方法计算了He^&lt；2&gt；，Be^&lt；2&gt；，Be^&lt；4&gt；，B^&lt；3&gt；，B^&lt；5&gt；，C^&lt；2&gt；，C^&lt；4&gt；，C^&lt；6&gt；，N^&lt；，C^&lt；2&gt；，C^&lt；4&gt；，C^&lt；6&gt；，N^&lt；2&gt；，N^&lt；3&gt；，N^&lt；5&gt；，N^&lt；7&gt；，Li^，Li^&lt；2&gt；，Li^&lt；3&gt；作为结果，解释了这些碰撞体系的碰撞能和峰的宽度。研究了共振位置与靶原子、入射离子和电荷的关系。此外，用谱方法得到了共振态的本征值和本征函数。用多通道小波包方法研究了系统的共振动力学，并成功地实现了共振现象的可视化。一般来说，靶原子的极化率越大，入射离子的电荷越高，系统的共振就出现在较高的碰撞能量处。然而，我们必须引起人们对势能曲线排斥现象的注意。我们的计算结果表明，在(He^&lt；2&Gt；Li，Na)碰撞体系中，共振出现在最高的碰撞能量(约0.3 eV)。由于成键势垒比极化势垒深得多，我们只考虑最低的Σ_g态和Σ_u态，计算了(H^H)碰撞体系在激光场中的截面。计算结果表明，在很高的碰撞能量(约2 eV)下会出现共振。

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).