Application of isomer-selected spectroscopy by ion-drift tube method to the intracluster reaction products

利用自行研制的质量和异构体分离检测系统，成功地分离了具有不同异构体结构的质量选择性碳团簇离子。在该系统中，离子漂移管室，这是充满氦气，位于飞行时间（TOF）质谱仪的无场区。团簇源产生的离子在静电场加速后注入细胞。然后，离子在电场的引导下穿过细胞，与背景He气体一个接一个地碰撞。由于离子在池中的迁移率取决于离子的几何截面，因此可以在池中分离出不同结构的离子。沿着该体系的发展，我们研究了具有多个异构体结构且能量相当的气相复杂体系。本课题主要完成了以下研究工作：1）Mg^+-XCH_3一价离子与卤代甲烷的光解离光谱和动力学; 2）碘化钠团簇离子与醇吸附质的光解离光谱; 3）含碱金属离子的体系的簇内聚合产物的结构鉴定;金属原子与多个丙烯腈分子通过光电离质谱和通过观察亚稳态，单分子解离反应，氮化硼团簇离子B_nN^+的多光子激发和解离反应机理及其途径。从这些研究中，我们发现了几种方法来确定每个异构体结构的多个异构体系统的激光光谱，沿着的直接分离方法，使用离子漂移管装置。本课题组正在对含金属原子的气相络合物或团簇的光解动力学和光谱进行更广泛的研究。

We have succeeded in separating mass-selected carbon cluster ions with different isomer structures, by using a home-made mass-and isomer-separation and detection system developed recently. In this system, an ion-drift tube cell, which is filled with helium gas, were located inside a field-free region of a time-of-flight (TOF) mass spectrometer. Produced ions in a cluster source were injected into the cell after acceleration by static electric fields. Then the ions were guided through the cell by an electric field, colliding with the background He gas one after another. We can separate the ions with different structure in the cell, because the ion mobility in the cell depends on the geometrical cross-section of the ion. Along with the development of this system, we have investigated gas-phase complex systems which have more than one isomer structures with comparable energy. The following studies have been done in this project ; 1)photodissociation spectroscopy and dynamics of magnesium monocation with methyl halide, Mg^+-XCH_3, 2)photodissociation spectroscopy of sodium iodide cluster ions with alcohol adsorbate, 3)structure identification of intracluster polymerization products for the system including an alkali-metal atom with plural acrylonitrile molecules by photoionization mass spectrometry and by the observation of metastable, unimolecular dissociation reactions, and 4)multiphoton excitation and dissociation reaction mechanism and its pathways from boron nitride cluster ions, B_nN^+. From these studies, we have found several ways to identify each isomer structure from plural isomer systems by laser spectroscopy, along with the direct separation method using the ion-drift tube apparatus. More extensive studies of photodissociation dynamics and spectroscopy for the gas-phase complexes or clusters containing metal atoms are now undergoing in our group.