氢分子振动态与铯分子基态碰撞中转动-振动能量转移

Rotation- vibration energy transfer between rovibrationally excited H_2(ν = 1,J = 3) and Cs_2( X^1∑_g^+)

利用受激拉曼泵浦将H2激发到v=1,J=3态,研究了H2(1,3)态与Cs2分子碰撞(1,3)态的弛豫及Cs2(X1∑+g)振动态的激发过程.利用相干反斯托克斯拉曼散射(CARS)检测H2的振转态分布,由CARS峰值得到密度比[H2(1,3)]/[H2(0,3)]和[H2(1,1)]/[H2(1,3)],由H2(ν=0)振转态的Boltzmann分布确定H2(0,3)的密度,由此得到[H2(1,3)]和[H2(1,1)]态的密度.激光诱导荧光光谱(LIF)确定被碰撞激发的Cs2(X1∑+g,ν″=11-15)各态.利用单模半导体激光作瞬时光吸收,对于ν″=11,12,13,14和15,积分吸收系数(单位:106cm-1s-1)分别是6.5,7.9,7.0,6.1和4.7,结合H2(1,3)的密度,得到H2(1,3-Cs2(X1∑+g,ν″)的转移速率系数,对于ν″=11-15,分别是(单位:10-13cm3s-1)1.4±0.6,1.7±0.7,1.5±0.6,1.3±0.5和1.0±0.4.利用吸收线Doppler增宽测量分别得到了Cs2(X1∑+g,ν″=11-15)的平动能.

The relaxation of H2( 1,3) by collision with Cs2 molecules has been investigated at T = 490 K. Particular focus is placed on understanding both the dynamical features and the kinetics of collision which are accompanied by energy transfer into the Cs2 vibrational and translational degrees of freedom,H2( 1,3) was prepared by stimulated Raman pumping. We have used the CARS( Coherent anti- stokes Raman Scattering) spectral technique to probe the internal state distribution of H2 molecules. From CARS spectral peaks population rations[H2( 1,3) ] / [H2( 0,3) ],[H2( 1,1) ] / [H2( 1,3) ]are obtained. From rotational Boltzmann distribution of ν = 0,these ratios indicate that [H2( 1,3) ]= 7. 8 × 1015cm- 3and [H2( 1,1) ]= 2. 2 × 1015cm- 3. LIF( Laser induce fluoresc ence) has been used to detect collisionally excited Cs2( X1∑+g,ν″). The densities of the Cs2( X1∑+g,ν″) were obtained by monitoring the transient absorption of the single- mode diode laser beam,turned to the B X transitions. Combining with density of the H2( 1,3),the rate coefficients for H2( 1,3)- Cs2( X1∑+g,ν″) processes have been determined. For ν″ = 11,12,13,14 and 15,they are( 1. 4 ± 0. 6) × 10- 13cm3s- 1,( 1. 7 ± 0. 7) × 10- 13cm3s- 1,( 1. 5 ± 0. 6) × 10- 13cm3s- 1,( 1. 3 ± 0. 5) × 10- 13cm3s- 1and( 1. 0 ±0. 4) × 10- 13cm3s- 1respectively. Doppler spectroscopy was used to measure the distribution of Cs2 recoil velocities for individual vibrational levels of the X1∑+gstate.