五氟乙烷的真空紫外光电离光解离  

Vacuum Ultraviolet Photoionization and Photodissociation of Pentafluoroethane

作　　者：杨斌[1] 黄超群[1] 杨锐[1] 卫立夏[1] 王晶[1] 王思胜[1] 单晓斌[1] 齐飞[1] 张允武[1] 盛六四[1] 王振亚[2] 郝立庆[2] 周士康[2] 

机构地区：[1]中国科学技术大学国家同步辐射实验室,合肥230029 [2]中国科学院安徽光学精密机械研究所环境光谱学实验室,合肥230031

出　　处：《物理化学学报》2005年第5期539-543,共5页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20273064);中国科学院知识创新项目资助~~

摘　　要：利用同步辐射真空紫外光电离结合飞行时间质谱对五氟乙烷(CHF2CF3)进行了光电离光解离的研究,测定了CHF2CF3的电离势及该分子主要碎片离子的出现势.结果表明:CHF2CF3的绝热电离势为(12.25±0.10)eV,主要碎片离子有CF2CF3+、CHFCF3+、CF2CF2+、CF3+、CHF2+、CHF+和CF+,其出现势分别为(13.93±0.10)eV,(15.25±0.10)eV,(15.12±0.10)eV,(13.30±0.05)eV,(13.05±0.08)eV,(19.17±0.10)eV和(19.56±0.15)eV.另外,用从头算分子轨道理论计算了解离电离过程中所有碎片的总能量,并给出了电子态及对称性.根据实验结果和理论计算,分析了可能的解离通道,并得到了分子及母体离子的键解离能等重要的热力学数据.The vacuum ultraviolet photoionization and photodissociation of pentafluoroethane have been studied by using synchrotron radiation. The ionization potential of pentafluoroethane is determined to be (12.25 0.10) eV. Photoionization efficiency (PIE) curves for CF2332232CF+,CBFCF+,CFCF+,CF+,CHF+,CHF+ and CF+ have been measured. The appearance potentials (AP) of these ions are obtained from their PIE curves, and they are (13.93 0.10) eV, (15.25 0.10) eV, (15.12 0.10) eV, (13.30 0.05) eV, (13.05 0.08) eV, (19.17 0.10) eV and (19.56 0.15) eV, respectively. In addition, the energetics of the dissociative photoionizations have been examined by ab initio Gaussian-3 calculations. The computational results are useful in establishing the dissociation channels near the ionization thresholds. According to the experimental results and the energies calculated by Gaussian-3 theory, the main possible pathways of the photodissociation have been analyzed. And the dissociation energies of the molecule and its cation have been derived from experiment and calculation.

关 键 词：五氟乙烷 光电离 出现势 解离能 

分 类 号：O621[理学—有机化学]