利用共振光电离技术和飞行时间质谱技术,观察到了复合物p-C6H4F2NH3(ND3)的共振双光子电离光谱。光谱分析表明,复合物分子间的伸缩振动频率为86.4cm由复合物的光解离机理以及伸缩模的失谐参数与键能的关系,获得了复合物电子激发态S1和基态S0的键能信息。Abinitio计算表明,p-C6H4F2…NH3(ND3)复合物的几何结构是:NH3分子中的N原子位于垂直于p-C6H4F2NH3(ND3)分子环面的对称轴(Z轴)上,距环面的高度为0.352nm;NH3的C3轴与p-C6H4F2的对称轴夹角是52.5°,且一个氢原子朝向环面;NH3可绕p-C6H4F2分子的Z轴近似的自由转动。键能计算值和预计存在的内转动与实验吻合。

We have studied theresonant two-photon ionizaition (R2PI) spectra of van der Waals complexes p-C6H4F2NH3...(ND3)through the S1←S0 transition withmass selectivity. Spectal analysis shows that the stretching frequencies of the complexesis about 86cm-1. From the photodissociation energy, we estimated the bond energy of the complexp-C6H4F2…NH3 in the S1 and S0 states. Abinitio calculation for p-C6/H4/F2/…NH3/ gives the following geometry: the N atom of NH3is located on the symmetry axis (Z-axis) and 0.353～nm above the benzene ring;the C3 axis of NH3is at an angle of 52.5° with the Z-axis of p-C6H4F2 withone of the hydrogen atoms pointing towards the benzene ring;the rotation of NH3around the Z-axis is nearly free. The calculataed bond dissociation energy and theprediction of internal rotation are consistent with our experimental results.