中文摘要：

利用阈值光电子-光离子符合飞行时间质谱研究了氯甲烷分子在13至17 eV激发能量范围内的光电离和光解离动力学.在此能量范围内,电离产生的CH3Cl＋离子处于A2A1和B2E电子激发态.两电子态均为完全解离态,可生成CH3＋和CH2Cl＋碎片离子,其中CH3＋是最主要的解离产物.拟合CH3＋离子的符合飞行时间质谱峰形,可以得到CH3Cl＋离子解离过程中释放的平动能分布,结果显示CH3Cl＋离子A2A1态解离生成CH3 ＋ 的过程接近直接解离机理,而B2E态的解离过程则具有统计解离的特征.此外,结合理论计算的势能面信息,我们推测在A2A1态出现的CH2Cl＋碎片离子来源于CH3Cl 分子自电离产生高振动激发的CH3Cl＋（X2E）离子统计解离过程.

英文摘要：

Using threshold photoelectron-photoion coincidence time-of-flight mass spectrometry, the photoionization and photodissociation of methyl chloride in the excitation energy range of 13-17 eV were investigated. CH3Cl＋ ions in the A2A1 and B2E excited states were generated, both of which were completely dissociative. CH; fragments were mainly produced while CH2Cl＋ fragment ions were observed as well. By fitting the time-of-flight profile the kinetic energy released distributions of CH; during the dissociation of the energy-selected CH3CI~ ions were obtained. The dissociation of the CH3CI~ （A2A1） ion followed rapid direct fragmentation while that of the B2E state showed statistical dissociation. Moreover, with the aid of the calculated potential energy surface the CH2Cl^＋ fragment ions observed in the A2A1 state were generated from the statistical dissociation of the high vibrational excited CH3Cl^＋ （X^2E） ions produced by the autoionization of the CH3CI molecule.