Investigation of Many Body Effect in Cluster Collisions

我们研究了以下涉及簇的碰撞反应，以阐明多体过程的机制。这些研究是在与德国比勒菲尔德大学H. O. Lutz教授的联合研究中进行的。研究了分子（氩和甲醇）和金属（钠）簇离子与稀有气体原子的碰撞诱导反应。在分子簇中，观察到高效的内部激发，这可以用目标原子与其中一个组成分子的相互作用来解释。在金属团簇中，内部激发效率较低，解离过程依赖于团簇大小。当一个簇与一个高能离子碰撞时，形成一个带多重电荷的簇离子，它通过库仑爆炸解离。我们开发了一种方法，从由此产生的碎片离子的空间和速度分布推断出初始簇的结构和解离动力学。研究了金属团簇Al_n +与有机分子异戊二烯的反应。吸附率的大小依赖关系与Al_n的电离势密切相关。这一事实表明电子从分子转移到Al_n^+.4。研究了（C_6F_6）_n^-和Al_n^-在硅表面的散射。碎片离子的大小分布揭示了簇和表面之间的电子转移。依赖于碎片大小的反冲速度表明，由于簇的多体性质，多次碰撞。提出了一个卢瑟福后向散射实验来研究在高能状态下表面与簇离子之间的相互作用。用He^+进行了初步实验。在上述研究的基础上，我们将启动簇-簇碰撞项目，阐明这些动力学过程中涉及的多体反应机制。

We have investigated the following collisional reactions involving clusters to elucidate the mechanisms of the many-body processes. The studies were carried out in the Joint Research with Prof. H. O. Lutz of Universitat Bielefeld, Germany.1.The collision-induced reactions of molecular (argon and methanol) and metal (sodium) cluster ions with rare gas atoms were studied. In the molecular clusters, highly efficient internal excitation was observed, which was explained by the interaction of the target atom with only one of the constituent molecules. In the metal cluster, the internal excitation was less efficient and the dissociation process was dependent on the cluster size.2.When a cluster collides with a high-energy ion, a multiply charged cluster ion is formed, which dissociates through the Coulomb explosion. We developed a method deducing the structure and the dissociation dynamics of the initial cluster from the space- and velocity-distributions of fragment ions thus produced.3.The reaction of metal clusters, Al_n^+, with an organic molecule, isoprene, was investigated. The size dependence of adsorptivity was closely correlated with that of the ionization potential of Al_n. This fact suggests electron transfer from the molecule to Al_n^+.4.The scattering of (C_6F_6)_n^- and Al_n^- from a silicon surface was studied. The size distribution of fragment ions revealed electron transfer between the cluster and the surface. The recoil velocity dependent on the fragment size suggests multiple collision due to the many-body nature of the clusters.5.A Rutherford backscattering experiment was proposed to investigate the interaction between a surface and a cluster ion in the high-energy regime. A preliminary experiment was performed with He^+.On the basis of the above studies, we will start a project of cluster-cluster collision and clarify the mechanisms of many-body reactions involved in these dynamical processes.