氟利昂F-113光解离和光谱研究

Studyon Photodissociation and Spectroscopy of Freon 113

已有实验得到了氟利昂F-113(C_2F_3Cl_3)在800nm飞秒激光脉冲作用下的飞行时间质谱图。计算了质谱图中各峰所占比例,分析了检测到的离子碎片,发现了C_2F_3Cl_3^+解离的三个主要通道。计算了各通道发生解离的能量差值和质谱图中主要离子中氯同位素的丰度比,所测丰度比接近大自然中氯同位素的丰度比3.13。利用程序Gaussian 09在B3LYP/6-311G++(d,p)基组水平上优化得到了C_2F_3Cl_3光解离过程中主要离子的稳定构型,计算其频率及能量,获得了红外光谱和各构型的单点能。对B3LYP/6-31G++(d,p)基组水平上得到的C_2F_3Cl_3和C_2F_3Cl_3^+稳定构型进行势能面扫描,发现C_2F_3Cl_3^+中的C—C(1-2)、C—Cl(2-3)键活性强于C—Cl(1-5)和C—F(1-7,1-8,2-6)键,易断键解离,在质谱图中形成最强或较强的峰,该结果与实验得到的飞行时间质谱图相吻合。

The time-of-flight mass spectrum of freon F-113 （C2F3C13） has been obtained by other researchersr experiment under action of a 800 nm sapphire {emtosecond laser, and three major dissociation channels of C2 Fa C1＋ are discovered by calculating the proportion of each peak in the mass spectrum and analyzing the detected fragment ions. The energy difference of each dissociation channel is calculated and the chlorine isotope abundance ratio of major ions in the mass spectrum approaches the natural abundance ratio of 3.13. Stable configurations of major ions in the Cz F3 C13 light dissociation process are obtained by the optimization at B3LYP/6-311G＋ ＋ （d, p） basis set level of Gaussian 09. The infrared spectrum and single point energy of each configuration are obtained through calculation of frequency and energy. The potential energy surface scan on stable configurations of CzF3C13 and C2F3C1＋ obtained by the optimization at B3LYP/6 31G＋＋ （d, p） basis set level of Gaussian 09 shows that the activity of C--C （l-Z） and C--C1 （2-3） bonds is stronger than that of C--C1 （1-5） and C F （1-7, 1-8, 2-6） bonds in C2F3C1＋. C C （1-2） and C--C1 （2-3） bonds are easy to break and dissociate, which is in coincidence with the strongest or stronger peaks in the mass spectrum obtained by the experiment.