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17eV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CH+3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.
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.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2011年第12期2749-2754,共6页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(10979042
21073173)
国家重点基础研究发展规划项目(973)(2007CB815204)资助~~
关键词
氯甲烷
光电离
光解离
飞行时间质谱
势能面
Methylchloride
Photoionization
Photodissociation
Time-of-flight mass spectroscopy
Potential energy surface
作者简介
Corresponding author. Email： xzhou@ustc.edu.cn; Tel/Fax： ＋86-551-3600031.
