低振动激发HeI_2分子振动预离解寿命和终转动态分布

THE VIBRATIONAL PREDISSOCIATION LIFETIME AND FINAL ROTATIONAL STATE DISTRIBUTION OF HeI 2 VAN DER WAALS MOLECULE FOR LOW VIBRATIONAL EXCITATION

用含时黄金规则波包法，对ＨｅＩ２分子在低初始振动激发（ｖ＜１２）态下振动预离解动力学作了全维量子力学计算。所预言的总衰变宽度和寿命与谱线宽和皮秒时间分解的实时态－态测量外推数据符合得相当好。计算的总衰变宽度对初始振动态ｖ是敏感的并呈现一种非线性关系。结果表明低振动激发ＨｅＩ２分子衰变模式仍应是量子力学的。除终态相互作用对决定终转动分布有重要作用以外，首次发现，低振动激发态的初始特性也能显著影响终转动态分布。

We have presented calculations of the total and partial decay widths of vibrational predissociation for a low vibrational ( v <12) excited HeI 2 complex for total angular momentum J =0. The time dependent golden rule quantum wave packet method has been used in our numerical three dimensional calculation. Predicted the total decay widths and lifetimes are in fairly good agreement with those extrapolated from linewidth measurements and real time state to state studies using picosecond pump-probe and molecular beam techniques. Computed total decay widths and lifetimes as a function of the initial v not only exhibit a highly nonlinear behaviour, but also are sensitive to the initial v . The results demonstrate that a quantum mechanical decay mode of predissociation for low vibrational excitation remains as well, where the variation in decay widths does not to be an effect due to a change in the dissociation mechanism. The evolution of rotational state distributions in time is explored by detailed inspection of the partial decay widths at the different propagation times. The final state interaction between the fragments is important for determing the final rotational state distribution. The dependece of the final rotational state distribution on the initial vibrational state v is first found to be clear and unique. A plausible explanation is given for why the final rotational state distributions are senitive to the initial vibrational states v based on the viewpoint of the dependence fo the rotational constant of I 2 on v