Molecular Wave Functions and Inelastic Atomic Collisions
Molecular Wave Functions and Inelastic Atomic Collisions
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分子波函数和非弹性原子碰撞
DOI：
10.1103/physrev.164.131
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发表时间：
1967
期刊：
影响因子：
--
通讯作者：
W. Lichten
中科院分区：
文献类型：
--
作者：
W. Lichten
给出了非弹性原子碰撞的理论解释，特别是原子电子壳层深度互穿的剧烈碰撞。基集由单粒子、氢-分子-离子轨道波函数的乘积组成。在临界核间距离处发生的大能量损失可以看作是分子轨道理论预测的内壳层电子促进的结果。能量损失、多重电离和快速电子抛射是交叉处MO单粒子能级跃迁的结果。列出了避免非绝热交叉的机制。碰撞后，原子处于狭窄的离散状态，同时有几个电子处于高度激发状态。这种类型的激发发生在重粒子碰撞或核裂变中，而不是在光子或电子轰击中。确定能量的快电子的存在被看作是当前模型的一个独特预测。碰撞后分离原子的电荷态之间缺乏相关性被认为是由于高激发的外层电子之间的相关能弱。MO模型与能量损失、快速电子能谱和临界核间距离位置等细节的一致性表明，纯统计模型的不足，以及等离子体振荡或其他特殊机制假设的必要性不足。这一分析的一个值得注意的特点是，玻恩-奥本海默近似已推广到涉及几百千伏核动能的碰撞。
A theoretical interpretation is given of inelastic atomic collisions, especially violent cases where the atomic electron shells deeply interpenetrate. The basis set consists of a product of single-particle, hydrogen-molecular-ion orbital wave functions. The occurrence of large energy losses at critical internuclear distances can be seen as a result of the promotion of inner-shell electrons predicted by molecular-orbital (MO) theory. Energy losses, multiple ionization, and fast-electron ejection happen as a result of transitions between MO single-particle energy levels at crossings. A list is given of the mechanisms which cause an avoidance of diabatic crossings. After the collision, the atoms are left in narrow, discrete states with several electrons simultaneously, highly excited. This type of excitation occurs in heavy-particle collisions or in nuclear fission, but not in photon or electron bombardment. The presence of fast electrons at definite energies is seen as a unique prediction of the present model. The lack of correlation between the charge states of the separating atoms after the collision is seen to result from the weakness of correlation energy among electrons in highly excited, outer shells. The consistency of the MO model with the details of energy losses, fast-electron spectra, and positions of critical internuclear distances indicates the insufficiency of purely statistical models and the lack of necessity of the assumption of plasma oscillations or other ad hoc mechanisms. A noteworthy feature of this analysis is that the Born-Oppenheimer approximation has been extended to collisions which involve nuclear kinetic energies of several hundred kV.