Coulomb explosion study for structure analysis of clusters.

在本研究中，分子靶通过高电荷态原子离子的碰撞而倍增电离，导致靶分子的爆炸性解离。通过碎片离子的位置灵敏飞行时间测量，确定了碎片离子解离后的速度矢量。这两个财政年度研究的目标分子是N_2、CO、CO_2和N_2O，它们是典型的简单分子。主要研究内容如下：(1)为了提高收集效率，安装了一种新的大尺寸位置灵敏检测阳极。通过测量Ar^&lt；8+-Ar碰撞形成的反冲离子来考察系统的性能。(2)Ar^&lt；8+&Gt；与N_2和CO的碰撞，研究了靶取向对电荷转移截面的影响。对三电荷双原子分子产生的碎片离子的详细分析表明，离子的角分布与俄歇电子的关联将是重要的。此外，平行于入射束的CO更有利于三个电子的俘获。(3)Ar^&lt；8+&gt；与CO_2发生碰撞。确定了两个碎片O离子和一个C离子在每个碎裂事件中的速度矢量，分别称为“VO_1”、“VO_2”、“VC”。考虑到弯曲模的零点振动，VO1与VO2夹角的直方图与电离前的分子结构一致。此外，VO1-VO2与Vc的夹角也与分子结构一致。通过比较不同碎片通道的结果，发现高电荷态产生的“VO1”、“VO2”、“Vc”往往能更好地反映CO_2的分子图像。(4)构建了适用于ECR装置的簇源。

In the present study, molecular targets are multiply ionized by the collision of highly charged atomic ions leading to explosive dissociation of the target molecules. By position sensitive time of flight measurements of the fragment ions, velocity vectors of the fragment ions just after the dissociation were determined. The target molecules studied in these two financial years were N_2, CO,CO_2, and N_2O as typical simple molecules. The summary of the study is as follows.(1) A newly constructed large size anode for position sensitive detection was installed for better collecting efficiency. The performance of the system was examined by measuring recoil ions formed by Ar^<8+>-Ar collisions.(2) Ar^<8+> was collided with N_2 and CO in order to study how the target orientation would affect the charge transfer cross section. The detailed analysis of the fragment ions produced from triply charged diatomic molecules shows that the correlation of angular distribution of ions with Auger electrons would be important. In addition, CO aligned parallel to the incident beam is found to be more favorable for three electron capture.(3) Ar^<8+> was collided with CO_2. The velocity vectors of the two fragment O ions and one C ion for each fragmentation event were determined which will be referred as "Vo1", "Vo2", "Vc", respectively. The histogram of the angle of Vo1 versus Vo2 was consistent with the molecular structure before ionization taking account of the zero point vibrations of bending mode. In addition, the angle of Vo1-Vo2 versus VC was also consistent with the molecular structure. By comparing the results among various fragment channels, "Vo1", "Vo2", "Vc" produced from higher charged states tend to give more proper molecular image of CO_2.(4) Cluster source for the use in the ECR facility was constructed.