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Coulomb explosion of molecules in slow collisions of highly charge ions

高电荷离子缓慢碰撞时分子的库仑爆炸

基本信息

批准号：
10640387
负责人：
OKUNO Kazuhiko
金额：
$ 2.18万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

In collisions of highly charged ions with atom and molecules the most dominant processes are charge transfer processes in which highly charged ions capture an electron or many electrons into their excited state levels from targets. Many investigators have studied on electron capture processes of highly charge ions in collisions with atomic targets, however, details of the capture processes for molecular targets have been little investigated till now, because molecular explosion processes are too complicate.In this project, we have developed a new double-coincidence time-of-flight (TOF) instrument for three particle coincident detection. The experimental technique is very powerful to resolve complex reaction mechanisms in collisions of multiply charged ions with molecules. Especially for diatomic molecules, all reaction processes can be resolved by this technique. Then, for collision systems of HeィイD12ィエD1+ and KrィイD18ィエD1+ with NィイD22ィエD2, OィイD22ィエD2, and CO targets, we have measured fragmentation of N2, C2 and CO in each electron capture processes and branching ratios for each reaction channel and kinetic energy release distribution for each fragmentation have been determined at some energies below 1keV/amu. Also, in the measurements of their collision energy dependence, we have found some new phenomena due to the post collision between projectile ions and target ions after collisions, where coincident ion pair peaks are splitting into two peaks and molecular ion peaks are shifting by getting momentum with decreasing of the collision energy. The observation of the post co9llision effects gives us important information to understand the collision dynamics.

在高电荷态离子与原子和分子的碰撞中，最主要的过程是电荷转移过程，即高电荷态离子从靶上俘获一个或多个电子到它们的激发态能级。高电荷态离子与原子靶碰撞过程中的电子俘获过程已经得到了很多研究者的研究，但由于分子爆炸过程过于复杂，对分子靶俘获过程的详细研究还很少，本课题研制了一种新型的双符合飞行时间(TOF)三粒子符合探测仪器。该实验技术对于解决多电荷离子与分子碰撞中的复杂反应机理是非常有效的。特别是对于双原子分子，所有的反应过程都可以用这一技术来解决。然后，对于HeィイD12ィエD_(1+)和KrィイD_(18)ィエD_(1+)与N_(ィイ)D_(22)ィエD_2、O_(ィイ)D_(22)ィエD_2和CO靶的碰撞体系，我们测量了N_2、C_2和CO在每个电子俘获过程中的碎裂，并在低于1keV/Amu的能量范围内确定了每个反应通道的支化比和每个碎裂的动能释放分布。此外，在碰撞能量依赖的测量中，我们还发现了一些新的现象，这是由于碰撞后入射离子与靶离子之间的碰撞，重合离子对峰分裂成两个峰，分子离子峰随着碰撞能量的降低而获得动量而移动。碰撞后效应的观测为我们理解碰撞动力学提供了重要信息。