氟利昂F1110的光解离质谱和光谱研究  

Study on Photodissociation Mass Spectrum and Spectrum of Freon 1110

作　　者：李静[1] 刘玉柱[1,2] 林华[1] 葛英健 何君博 秦朝朝[3] 

机构地区：[1]南京信息工程大学江苏省大气海洋光电探测重点实验室,江苏南京210044 [2]江苏省大气环境与装备技术协同创新中心,江苏南京210044 [3]河南师范大学物理与材料科学学院,河南新乡453007

出　　处：《激光与光电子学进展》2017年第8期325-330,共6页Laser & Optoelectronics Progress

基　　金：国家自然科学基金(11304157;11504175;11404411);江苏省六大人才高峰高层次人才项目(2015-JNHB-011);南京信息工程大学大学生实践创新训练项目(201610300042)

摘　　要：利用飞行时间质谱技术得到了氟利昂F1110(C_2Cl_4)在400nm飞秒脉冲激光作用下的飞行时间质谱图,发现了C_2Cl_4^+、C_2Cl_3^+和C_2Cl_2^+这三种主要的碎片离子。利用密度泛函理论在B3LYP/6-311G++(d,p)基组水平上进一步计算和分析了C_2Cl_4^+在光解离过程中解离通道的能量变化,得出C_2Cl_4^+在光解离过程中需要吸收能量,说明C_2Cl_4^+在大气层中比较稳定。与已有实验得到的C_2Cl_4在800nm飞秒脉冲激光作用下的质谱图进行比较,并通过计算碎片峰中各主要离子的比例以及氯同位素的丰度比发现,C_2Cl_4在红外光辐射下更易发生解离。采用同样的基组对C_2Cl_4和C_2Cl_4^+中的C—Cl键进行势能面扫描,得到其鞍点,发现当C_2Cl_4解离生成C_2Cl_4^+时,C—Cl键的活性变高,更易断键解离。计算和分析了C_2Cl_4^+的红外光谱和拉曼光谱,利用从头算CIS方法得到了C_2Cl_4^+的紫外可见吸收光谱。Time-of-flight mass spectrum of freon 1110 （C2Cl4） under action of 400 nm femtosecond laser pulse is obtained by time-of-flight mass spectrometry technology. Three major fragment ions,C2Cl4^＋ , C2Cl3^＋ and C2Cl2^＋ are discovered in the mass spectrum. Based on the density functional theory, the energy changes in dissociation channels of Cz C14＋ during photodissociation process are further calculated and analyzed at the basis set of B3LYP/6-311G＋＋ （d, p）. The results show that C2Cl4^＋ needs to absorb energy during photodissociation process, which indicates that C2Cl4^＋ is more stable in the ozone layer. Besides, compared with the mass spectrum of C2Cl4 obtained with 800 nm femtosecond pulse laser which has been experienced by other researchers, and through calculating the proportion of each peak to total peak area and the chlorine isotope abundance ratio of major ions in the mass spectra, it is found that C2Cl4 is more likely to dissociate under infrared light radiation. Moreover, the potential energy surfaces of C2Cl4^＋ and C2Cl4^＋ about C-Cl bond are scanned via the same basis set, and the saddle points are obtained. It is found that the activity of C-Cl bond of C2Cl4^＋ becomes higher and the C-C1 bond is easier to break than that in C2Cl4. Infrared spectrum and Raman spectrum of C2Cl^＋ are calculated and analyzed, and UV-VIS spectrum is obtained with CIS method.

关 键 词：光谱学 氟利昂 光解离 飞行时间质谱 

分 类 号：O433.3[机械工程—光学工程]