高振动激发态KH(X^1∑^+,V=14～21)与CO_2碰撞中的振动-转动能量转移

Vibrational to rotational energy transfer between KH(X^1∑^+,V=14～21) and CO_2 in collision

利用泵浦-探测技术研究高振动激发态KH(V=14~21)分子与CO_2的振动-转动碰撞转移过程。脉冲激光激发KH分子至高位振动态,与CO_2发生振动-转动能量转移,使CO_2高位转动态得到布居,通过测量CO_2(00~00,J=32~48)转动态分布,得到其平均转动能和平均转动能变化,发现振动量子数V从14增加至21时,CO_2平均转动能变化增加了2.33倍;测量CO_2转动能级的多普勒增宽吸收线,得到V=14和20时,其获得的平均平动能大体随J增大而线性增大;最后,在单一碰撞条件下,测量KH(V=14~21)与CO_2(00~00,J)的振动-转动碰撞能量转移速率系数,结果显示V=19的总碰撞速率系数是V=14的4.5倍,而V>19则呈下降趋势。

The processes of vibration-rotation energy transfer between highly vibrationally excited KH （V=14～21） and CO2 were studied by using the pump-probe technique. KH is formed by the K （5P）＋H2 reaction. The pulse laser prepares KH in the highly vibrational levels. Energy gain into CO2 resulting from collisions with excited KH was probed by using laser overtone spectroscopy technique. The rotational temperatures of CO2 （00^00, J=32～48） states were obtained. The average rotational energy of the scattered CO2 molecules is increased by a factor of 2.33 when KH level V=14 increases to V=21. The nascent distributions of recoil velocities for collisions were determined from stimulated absorption line profiles of individual CO2 rotational states. The average translational energy of the scattered CO2 molecules is increased roughly linearly as a function of CO2 J state. Under single collision conditions, state-specific energy transfer rate coefficients for collisions of highly excited KH with CO2 were obtained. For V=19, the integrated rate coefficients kint increases by a factor of 4.5 to V=14, but when V〉19, it decreases roughly.