Tokue Ikuo, Ebina Shingo, Kanai Megumi, Nanbu Shinkoh
Department of Chemistry, Faculty of Science, Niigata University, Ikarashi, Niigata 950-2181, Japan.
J Chem Phys. 2007 Jan 28;126(4):044313. doi: 10.1063/1.2431653.
Transition probabilities were evaluated for the X (1)A(1)-A (1)B(1) and A (1)B(1)-B (1)A(1) systems of GeH(2) and GeD(2) to analyze the X-->A-->B photoexcitation. Franck-Condon factors (FCFs) and Einstein's B coefficients were computed by quantum vibrational calculations using the three-dimensional potential energy surfaces (PESs) of the X (1)A(1), A (1)B(1), and B (1)A(1) electronic states and the transition dipole moments for the X-A and A-B systems. The global PESs were determined by the multireference configuration interaction calculations with the Davidson correction and the interpolant moving least squares method combined with the Shepard [Proceedings of the 1968 23rd ACM National Conference (ACM, New York, 1968)] interpolation. The barriers to linearity correcting the spin-orbit interaction are evaluated to be 22,000 cm(-1) for the X state, 6300 cm(-1) for the A state, and 560 cm(-1) for the B state. The obtained FCFs for the X-A and A-B systems indicate that the bending mode is strongly enhanced in the excitation since the equilibrium bond angle greatly varies within the three states. The photoexcitation and fluorescence spectra calculated for the X-A system agree well with the observed spectra. The theoretical lifetimes for lower vibrational levels of the A and B states were calculated from the fluorescence decay rates for the A-X, B-A, and B-X emissions, and the lifetimes for the A state are in good agreement with the observed values except those affected by predissociation.
为了分析X(1)A(1)→A(1)B(1)和A(1)B(1)→B(1)A(1)体系的锗氢化物（GeH₂）和锗氘化物（GeD₂）的光激发过程，对跃迁概率进行了评估。使用X(1)A(1)、A(1)B(1)和B(1)A(1)电子态的三维势能面（PESs）以及X - A和A - B体系的跃迁偶极矩，通过量子振动计算来计算弗兰克 - 康登因子（FCFs）和爱因斯坦B系数。全局PESs是通过带有戴维森校正的多参考组态相互作用计算以及结合谢泼德[1968年第23届美国计算机协会全国会议论文集（美国计算机协会，纽约，1968年）]插值的插值移动最小二乘法确定的。评估得出，校正自旋 - 轨道相互作用的线性化势垒对于X态为22000 cm⁻¹，对于A态为6300 cm⁻¹，对于B态为560 cm⁻¹。对于X - A和A - B体系所获得的FCFs表明，由于在这三个态中平衡键角变化很大，弯曲模式在激发过程中被强烈增强。为X - A体系计算的光激发光谱和荧光光谱与观测光谱吻合得很好。根据A - X、B - A和B - X发射的荧光衰减率计算了A态和B态较低振动能级的理论寿命，除了那些受预解离影响的寿命外，A态的寿命与观测值吻合良好。
