复合物o-C_6H_4F_2·Ar的电子S_1态的内部van der Waals振动

Intermolecular van der Waals Vibrations of o-C_6H_4F_2·Ar Complex in the S_1 State

报道了复合物o—C6H4F2·Ar的电子S1态内部vanderWaalss（edW）振动的实验和理论研究。在超声束中，利用双光子共振电离光谱和飞行时间质谱技术，揭示了S1←S0电子态跃迁涉及内部wdW振动的3个谱带（＋16.1、＋41.5、＋50.5cm－1）。光谱分析表明，谱线＋16．1cm-1是Ar沿o—C6H4F2分子对称面内的振动模的基频跃迁;谱线＋41．5cm-1是Ar沿垂直于环面的振动模的基频跃迁;谱线＋50．5cm-1是Ar沿垂直于对称面的振动模的第一泛频跃迁。用三维线性谐振子波函数作为基和势函数取为Lenard—Jones势，进行了复合物o—C6H4F2·Ar的wdW振动能级理论计算，所获得的结果支持了光谱归属．对比p—C6H4F2·Ar和o—C6H4F2·Ar中的Ar原子vdW振动发现，2个F原子在环面上的相对位置对Ar沿垂直于环面的振动力常数影响不大，但对Ar沿平行于环面的两种振动有较大的影响。

A combined experimental and theoretical study of the intermolecular vibrations of o-C6H4F2.Ar van der Waals complex is reported. The three bands of intermolecular van der Waals vibrations, Which are from the electronic trasnition (S1←S0)are exhibital. Using resonant two-photon ioization spectrometry,together with time-of-flight mass spectrometry, in supersonic molecular beam. For complex 0-C6H4F2Ar, van der Waals vibration levels are calculated by the quantUm method of linear-combination of three-dimensional harmonic oscillator products and Lennard-Jones potential, which is very close to the experimental spectrum, The vibration of atom Ar in 0-C5H4F2. Ar compare with that in p-C6H4F2 Ar, which the vibrational force constant along the direction perpendicular to the ring plane is indepent on the relative position of two atoms F in-ring plane, but the two vibrational force constants,along the direction parallel to the ring plane, are related to closely the position of two atoms F in the ring plane.