532nm激光作用下甲基异丙基酮的电离解离研究  

Study on multiphoton ionization and dissociation of methyl isopropyl ketone at 532 nm

作　　者：刘妮[1] 孔祥和[1] 杨建春[1] 

机构地区：[1]曲阜师范大学物理工程学院,曲阜273165

出　　处：《原子与分子物理学报》2010年第6期1117-1122,共6页Journal of Atomic and Molecular Physics

基　　金：曲阜师范大学科研启动基金

摘　　要：在532 nm激光波长下,利用时间飞行质谱(TOF-MS)对甲基异丙基酮的多光子电离解离机制进行了研究.实验结果显示,母体分子首先发生α断裂并且吸收(2+2)个光子到达离子态.主要的质谱峰C_2H_3^+,CH_3COC_3H_7^+,CH_3^+等在质谱图中清晰可见.结合Guassian03,运用HF/3-21G、CIS/3-21G对基态和激发态的构型进行了优化和频率计算,发现激发态的碳氧键变为介于碳氧单键和双键之间特殊键,并用QST2方法找到了其中的过渡态,对三个状态的几何结构参数进行了分析得出了其解离过程是α键断裂和基团构象转化协同进行的结论.By laser mass spectroscopy, the multiphoton ionization-dissociation （MPID） of methyl isopropyl ketone are studied at 532 nm through analysis of the time of flight mass spectrum （TOF-MS）. The experiment shows that the parent molecule first occurs a-cleavage and absorbs （2＋2） photons to get to ion state. The main mass spectrum（MS） peak products such as C2H3O＋ , CH3COCaH＋ ,CH＋ etc can be seen clearly at MS. The comformation of the ground state and excited state also are optimized at HF/3- 21G level and HF/3-21G ＋ level, and find the carbonyl bond changes to a special bond that between carbonoxygen single bond and double bonds. The transition state is also investigated by using QST2 method, while compared the variation of conformation with the ground state and excitated state. The results show that the bond broken process in concert with the variations of configuration is onestep process.

关 键 词：TOF-MS 多光子电离解离 能量 几何构型 

分 类 号：O561.3[理学—原子与分子物理]