多原子分子受激光激励后振动分布的模型计算

以SF_6分子为例, 进行了多原子分予受脉冲红外激光激励之后, 其瞬态振动布居的模型计算。本模型可从实验测得的红外荧光或吸收光潜, 反演出与这些光谱相应的振动分布。反之亦然。与同类模型相比, 本模型的计算精度高, 可精确地生成振动跃迁几率矩阵, 且可计算受激光激励后分子在任一时刻的振动分布。用此模型, 首次获得SF_6分子低温条件下(20 K)的可转动分辨的吸收光谱和荧光光谱。

NUMERICAL MODELING OF THE VIBRATIONAL POPULATION DISTRIBUTION OF POLYATOMIC MOLECULES EXCITED BY IR LASERS

A computing model is presented for the calculation of the transient population distribution of polyatomic molecules excited by an IR laser pulse, SF_6 has been used as an example. This model allows the calculation of the vibrational energy distributions from the observed IR fluorescence or absorption spectrum, and vice versa. The thermal vibrational distribution calculated by this model from the mea- sured spectrum of SF_6 at 300 K is in good agreement with the Boltzmann distribu- tion (Table 1). The present model has a few advantages over an earlier study~1], such as higher precision of computation, accurate generation of the vibrational transition matrix and being capable of calculating the transient vibrational population distribution at any instant after laser excitation. Using this model a rotationally resolved spectrum of SF_6 at 20 K has been obtained for the first time.