高振动激发LiCs与CO_2碰撞中的振动-转动能量转移

Vibrational to rotational energy transfer in highly vibrationally excited LiCs-CO_2 collisions

受激发射泵浦得到的LiCs高位振动态与CO_2碰撞,研究了LiCs不同能量对碰撞能量转移过程的影响.利用高分辨率瞬时激光感应荧光(LIF)测量得到CO_2(0000,J=2-74)原生转动态分布.转动布居数的半对数描绘给出了一个双指数结构,得到了一个T_a=660±73K[对LiCs(E=4300cm^(-1))]和550±61K[对LiCs(E=3700cm^(-1))]的低能分布,一个T_b=2380±261K[对LiCs(E=4300cm^(-1))]和1980±217K[对LiCs(E=3700cm^(-1))]的高能分布,低能分布属于弹性或弱非弹性碰撞,高能分布属于强非弹性碰撞.转动分布对LiCs能量是敏感的.但弹性与非弹性分支比基本是相同的.在一次碰撞的条件下,测量了各J态的出现和倒空速率系数,它们仅弱依赖于LiCs激发能.出现和倒空速率系数对不同LiCs能量基本一致,是振动-转动/平移弛豫轨道的重要证据.

Highly vibrationally excited LiCs was achieved by stimulated emission pumping. The full state -re- solved distribution of scatted CO2 （0000） molecules from collisions with excited LiCs is reported. How internal energy content impacts the dynamics for collisional quenching of high energy molecules are investigated. Nascent rotational state distributions for scatted C02 （0000） molecules with J = 2 - 74 were measured using high resolution transient laser induced fluorescence （LIF）. The semilog plot shows evidence of a biexponential distributiola. The fitting yields a low energy distribution Ta and a high energy distribution Tb. For E = 4300cm -1, we find that To = 660 ±73K and Tb =2380 ±261K, compared to Ta =550 ±61K and Tb = 1980 ±217K for E = 3700cm-1. The spread of the rotational distribution is sensitive to donor energy, but the branching ratio for elastic and inelastic collisions is the same for both donor energies. The overall appearance and depletion rates constants were meas- ured. The measured collision rate constants are only weakly dependent on changes in LiCs energy. The agree- ment of the overall appearance and depletion rates at two different LiCs energies provides evidence for the impor- tance of vibration -rotation/translation relaxation channel.