A Study of Site-Specific Fragmentation by Using Core Excitation・with the Aim of Application to Molecular Knife-

以应用于分子刀为目的，利用电子-离子重合光谱研究了有机硅分子（如F_3SiCH_2CH_2Si(CH_3)_3）、N_2O、CF_3SF_5和甲酸二聚体（HCOOH）_2在气相和凝聚相中的核电离引起的位点特异性断裂。采用从头算分子轨道法进行理论描述。由Si:2p核能级光电离引起的位点特异性断裂。采用高分辨率能量选择电子-光子-光子三重重合能谱法研究了F_3SiCH_2CH_2Si(CH_3)_3蒸气。与3个甲基键合的Si原子以2p光离产生F_3SiCH_2CH_2^+-Si(CH_3)3^+离子对，与3个F键合的Si原子以2p光离产生含SiF^+离子对。在Si:1s电离中，位点特异性降低。N_2O的N:1s光电离引起的位点特异性离子解吸还不清楚。在N_2O中相互连接的两个氮位点之间的有效电子迁移是导致离子解吸的位点特异性消失的原因。

With the aim of application to molecular knife, we studied site-specific fragmentation caused by core-ionization of organosilicon molecules (for example, F_3SiCH_2CH_2Si(CH_3)_3), N_2O, CF_3SF_5, and formic acid dimer (HCOOH)_2 by means of electron-ion coincidence spectroscopy in the vapor phase and condensed phase. The ab initio molecular orbital method was used for the theoretical description.Site-specific fragmentation caused by Si:2p core-level photoionization. of F_3SiCH_2CH_2Si(CH_3)_3 vapor was studied by means of high-resolution energy-selected-electron photoion-photoion triple-coincidence spectroscopy. F_3SiCH_2CH_2^+-Si(CH_3)3^+ ion-pairs were produced by the 2p photoionization of the Si atoms bonded to the three methyl groups, and SiF^+-containing ion-pairs were produced by the 2p photoionization of the Si atoms bonded to the three F atoms.The site-specificity was reduced in the Si:1s ionization. The site-specific ion desorption caused by N:1s photoionization of N_2O was not clearly revealed. The effective electron migration between the two nitrogen sites, which are connected with each other in N_2O, would be responsible for the disappearance of the site-specificity for the ion desorption.