激发态Cs_2和H_2的电子—振转能级的碰撞转移

The Electronic-to-Rovibrational Levels Energy Transfer between Electronically Excited Cs_2 and H_2

利用相干反斯托克斯拉曼光谱(CARS)探测技术,研究了激发态Cs2与H2间的电子—振转能级的碰撞转移。用波长为532 nm和中心波长为716 nm的两束激光同时聚焦到样品池中,扫描CARS谱确认了H2分子的S支(△v=1,△J=2)仅在v=1,J=4,5及v=2,J=3,4能级上有布居,用n1、n2、n3、n4分别表示(2,4)、(2,3)、(1,4)及(1,5)上的粒子数密度。从CARS线的峰值得到n2/n1、n3/n1、n4/n1分别为6.34±1.27、3.66±0.73和1.45±0.29。转移能配置到振动、转动和平动的比例分别为0.44、0.06和0.50,能量主要分配在振动和平动上。在T=523 K和PH2=2.5×103Pa条件下,通过求解速率方程组和对时间分辨CARS线轮廓的分析,得到碰撞转移速率系数k1=(6.0±1.2)×10-14cm-3s-1和k2=(4.0±0.8)×10-13cm-3s-1。

Using the CARS （coherent anti-Stokes Raman spectroscopy） detection technique, we have investigated the electronic-to-rovibrational levels energy transfer between electronically excited Cs2 and H2. In this CARS experiment, the S--branch（△v = 1, △J =2） transition of H2 are excited by two laser pulses, the pump and the Stokes, respectively, centered at 532 and 716 nm. The internal state distribution of collisionally populated H2 has probed. The scanned CARS spectra reveal that during energy transfer processes H2 molecules are produced only at the v= 1, J = 4,5 and v= 2, J =3,4 rovibrational levels. From scanned CARS spectral peaks the population ratios are obtained. The n2/n,n3/n2and n4/nl are 6.34-bl. 27,3.66q-0.73 and 1.45：t：0.29,respectively, where nl ,n2 ,n3 and n4 represent the number densities of H2 at the rovibrational levels（2,4）,（2,3）,（1,4）,and （1,5）, respectively. The relative fractions （〈fv〉 ： 〈fr〉： 〈fr〉） Of average energy disposal are derived as （0.44, 0.06, 0.50）, having major translational and vibrational energy release. Through shape simulation of the time-resolved CARS profiles under a simple kinetic model at the experimental conditions of T= 523K and P= 2.5 ）〈 103 Pa, collisional transfer rate coefficients kl = （6.0-4- 1.2） ）〈 10^-14 cm^-3s^-1 s-1 and kz = （4. 0-/- 0.8） X 10^-13 cm^-3 s^-1 have obtained.