Cs（6^2D5/2）与H2反应生成的CsH分子的转动和振动态分布  

Rotational and Vibrational State Distributions of CsH in the Reactions of Cs（6 ^2D5/2） with H2

作　　者：王大贵[1] 周冬冬[1] 王雪燕[1] 穆尼赛[1] 戴康[1] 沈异凡[1] 

机构地区：[1]新疆大学物理科学与技术学院,新疆乌鲁木齐830046

出　　处：《光谱学与光谱分析》2010年第5期1157-1160,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(10664003)资助

摘　　要：利用激光泵浦-探测技术,在样品池条件下,研究了Cs(6D5/2)态与H2反应生成的CsH分子基电子态的转动和振动的量子态分布。在Cs-H2混合蒸气中,脉冲激光双光子激发Cs(6D5/2)态,另一台调频脉冲激光器扫描CsHX1Σ+(v″,J″)→A1Σ+(v′,J′=J″±1)吸收线,发现CsH分子只有v″=0和1上的振动带上有布居而不布居在v″>1的振动带上。v″=0和1上的转动带分布呈现单峰结构,其峰值位于J″=6～8处,转动带分布轮廓与池温下的统计分布接近。转动Boltzmann温度分别为(458±20)K(对v″=1)和(447±18)K(对v″=0),得到的CsH分子的转动温度稍低于池温。从转动态分布得到v″=1与v″=0上布居数之比约为0.897,从而计算出CsH基电子态上的平均转动能<ER>和平均振动能<EV>,有效能减去平均振转能得到平均平动能<ET>。CsH分子3种能量的相对比值<fT>∶<fV>The nascent quantum state distributions of the CsH product resulting from the reaction Cs（6D5/2） with H2 were determined using a laser pump-probe technique in a five-arm crossed heat-pipe oven. Cs-H2 mixture was irradiated with pulses of 885.4 nm radiation from a OPO laser, populating 6D5/2 state by two-photon absosption. Laser induced fluorescence was used to detect CsH molecules directly at the collision volume by scanning pulse tunable dye laser over X^ 1Σ＋（v″,J″）→A 1Σ＋（v′,J′=J″±1） absorption line. The vibration bands （v″=0, v′=6） and （v″=1, v′=9） were chosen. For the investigated reaction, the nascent CsH product molecules were found to populate the lowest two vibrational （v″=0, 1） levels of the ground electronic state but could not be detected in any higher vibrational state. Rotational distributions of CsH products obtained for v″=0 and 1 states appear to be monomodal , peaking in J=6-8. The rotational population profile is roughly consistent with a statistical distribution at the system temperature. A plot of logarithm of relative population of states J divided by the degeneracy factor （2J＋1） against J（J＋1） was yielded. The linearity of the plot establishes the Boltzmann form for rotational distributions of both the v″=0 and 1. The rotational temperatures are （458±20） K and （447±18） K for v=0 and 1, respectively. The nascent CsH rotational temperatures were found to be slightly below the cell temperature. The relative vibrational population was determined to be 0.527 and 0.473. The average vibrational and rotational energy release can be computed. The relative fractions 〈fV〉, 〈fR〉 and 〈fT〉 of average energy disposal were derived as 0.25, 0.10 and 0.65 respectively, having a major translation energy release. All of the above results support the assumption that the Cs（6^ 2D5/2）-H2 reaction occurs primarily in a collinear geometry by a harpoon mechanism but not an insertion.

关 键 词：激光化学 三体反应 激光诱导荧光 布居数分布 Cs-H2 

分 类 号：O561.5[理学—原子与分子物理] O644.1[理学—物理]