HXD中XH拉伸振动的振动跃迁偶极矩方向的理论研究

本文利用局域模研究了“重轻”体系简单分子XH伸缩振动的实验振动光谱. 键偶极方法进一步为实验光谱分析提供了帮助(假设XH伸缩振动的跃迁偶极矩沿着XH键方向排列). 通过局域模和多维简正模对HOD，HND^-，HCD，HSD，HPD^-和HSiD的XH伸缩振动的理论计算， XH伸缩振动的局部1D图片可以用于分析跃迁偶极矩倾斜角度. 在HOD分子中，OH伸缩振动的跃迁偶极矩远离OH键并且向远离OD键的方向倾斜；在HSD，HND^-，HPD^-，HCD和HSiD分子中的XH伸缩振动远离OH键，但朝向OD键，表明键偶极近似法不能很好地适用于“重轻体系”分子，重原子X可以影响跃迁偶极矩方向. 利用分子中原子理论分析了偶极矩的变化.

Theoretical Study on Direction of Vibrational Transition Dipole Moment of XH Stretching Vibration in HXD

Experimental vibrational spectra of heavy light XH stretching vibrations of simple molecules have been analyzed using the local mode model. In addition, the bond dipole approach, which assumes that the transition dipole moment (TDM) of the XH stretching mode is aligned along the XH bond, has helped analyze experimental spectra. We performed theoretical calculations of the XH stretching vibrations of HOD, HND^-, HCD, HSD, HPD^-, and HSiD using local mode model and multi-dimensional normal modes. We found that consistent with previous notions, a localized 1D picture to treat the XH stretching vibration is valid even for analyzing the TDM tilt angle. In addition, while the TDM of the OH stretching fundamental transition tilted away from the OH bond in the direction away from the OD bond, that for the XH stretching fundamental of HSD, HND^-, HPD^-, HCD, and HSiD tilted away from the OH bond but toward the OD bond. This shows that bond dipole approximation may not be a good approximation for the present systems and that the heavy atom X can affect the transition dipole moment direction. The variation of the dipole moment was analyzed using the atoms-in-molecule method.