首次考虑了两个中间态对激光感生碰撞能量转移的影响，发展了激光感生碰撞能量转移的四能级理论模型，推导出态振幅的运动方程，并给出碰撞截面的近似表达式。通过对Eu-Sr和Cs-Sr系统的数值计算表明，当频率差｜ω21｜的大小和｜ω43｜可以相比时，利用三能级近似理论就难以获得令人满意的计算结果，而四能级理论模型则适合于任何情况下的激光感生碰撞能量转移。

In this paper a four level model of laser induced collisional energy transfer (LICET) is presented in which the effects of the two intermediate states are considered. The equations of motion for the probability amplitudes of the four states are then obtained. And the analytical expression of the cross section for the LICET transition is derived. The results of numerical calculations in Eu-Sr and Cs-Sr systems show that the conventional three level theory cannot be expected to provide an adequate description of the cross section of the LICET transition if the frequency difference ｜ω21｜ is comparable to the frequency difference ｜ω43｜. But the four-level model can be used to describe the LICET process in all cases.