二氧化铬阴离子光电子能谱的理论研究

Theoretical investigation on the photoelectron spectra of the photodetachmentprocess of the CrO_2^- anion

凭借密度泛函理论,采用不同基组对中性分子CrO2的基态(X3 B1)以及阴离子CrO2-的基态(X4B1)进行几何优化和振动频率分析;应用量化计算得到的力常数及结构和光谱参数,基于推得的两维四模Franck-Condon重叠积分的代数表示,对CrO2(X3 B1)-CrO2-(X4 B1)的光脱附过程进行Franck-Condon分析和光谱模拟,理论上得到光电子能谱的谱线相对强度及振动结构分布,理论谱与实验测得的二氧化铬阴离子光电子能谱达到一致,并对光电子能谱的振动结构进行归属及热带分析;另外,在光谱模拟过程中通过迭代Franck-Condon分析过程,推得CrO2-(X4 B1)与CrO2(X3 B1)平衡几何结构之差:ΔR(Cr-O)=0.05,Δ∠(O-Cr-O)=12°.

Geometry optimization and harmonic vibrational frequency calculations were performed on the X 3B1 state of CrO2 and X4B1 state of CrO-2 by using the Density Functional Theory with various basis sets. The adiabatic electron affinity of CrO2 was investigated by using BPW91 and B3PW91 methods extrapolated to the complete basis set limit. Frank-Condon analyses and spectral simulations were carried out on the CrO2（X3B1）-CrO-2（X4B1） photodetachment process. The simulated photoelectron spectra of CrO-2 are in excellent agreement with the observed ones. While the Duschinsky effect plays a minor role and can be neglected. In addition, the equilibrium geometry differences between the ion and neutral,ΔR（Cr-O）= 0.05  and Δ∠（O-Cr-O）=12°, were deduced by employing an iterative Franck-Condon analysis procedure in the spectral simulation.