摘要
研究了入射光波长与S0 →S2 跃迁共振的情形下 ,卟啉镍配合物 (NiP)的振动拉曼光谱。用时间域方法计算了NiP的共振拉曼强度和吸收光谱。结果表明 ,相对于基态 ,S2 态NiP的分子构型沿着ν8和ν2 简正坐标有较大的位移。这些简正坐标主要涉及卟啉环的CαCm 键和CβCβ 键伸缩运动 ,以及CαCmCα 变角运动。与基态相比 ,S2 态的CβCβ、CαCm 和CαN键分别增大 0 .2 7、0 .14、0 .0 7pm ,而CαCβ 键则减小 0 .2 0pm ,与前人的赝势分子轨道计算 (SPMO)结果相近。还从RR强度角度讨论了S2 态的Jahn -Teller畸变。
Resonance Raman intensities and UV visible absorption spectrum of nickel(II) porphyrin (NiP) were analyzed with time dependent formulas under standard approximations for Condon mechanism of enhancement. The resultant dimensionless displacements on S 2 state are comparable with those obtained by Spiro et al. from Kramers Kronig transform methods. It was deduced from the calculations that there are large dimensionless displacements on the excited state along ν 8 and ν 2 coordinates. These normal modes consist of relatively large components of C βC β, C α C m bond stretching and C αC mC α bond bending motions. Compared with the ground state, the average bond lengths of C βC β, C αC m, and C αN bonds at S 2 state increase respectively by 0.27, 0.14, and 0.07pm,while that of C αC β bond decreases by 0.20pm,which are well in coincident with the SPMO calculations in literature.
基金
国家自然科学基金!资助项目 (2 98730 4 3)
教育部博士点专项基金!资助课题&&
