Wang Jun, Wang Min, Dai Kang, Wang Qian, Shen Yi-Fan
Department of Physics, Xinjiang University, Urumqi 830046, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2009 Oct;29(10):2610-3.
Rb vapor, mixed with H2 or He, was irradiated in a glass fluorescence cell with pulses of radiation from a YAG-laser-pumped OPO laser, populating 5D or 7S state by two-photon absorption. The temperature dependence of the cross sections for 5D-7S transfer induced by collisions with He atoms and H2 molecules was determined using methods of atomic fluorescence. The resulting fluorescence included a direct component emitted in the decay of the optically excited state and a sensitized component arising from the collisionally populated state. At the different densities, the authors have measured the relative time-integrated intensities of the components and fitted a three-state rate equation model to obtain the reactive and nonreactive cross sections for Rb(7S-5D)-H2, He collisions. The cross sections of transfer for Rb(7S)+H2-->Rb(5D)+H2 decrease with increasing T. The cross sections for 5D-->7S increase with increasing T. At the different temperatures, the cross sections of transfer for (7S-5D)-He collisions coincide with the principle of detailed balance. The total transfer rate coefficients out of the 7S or 5D state for He were small. The total quenching rate coefficient out of the 7S or 5D state was much larger for H2. In the case of H2, the quenching rate coefficient corresponds to reaction and nonreactive energy transfer. In reaction of Rb(7S, 5D)+H2-->RbH+H, the ratio between the reactive cross sections was found to be sigma(-)[Rb(7S)+H2]/sigma(-)(Rb(5D)+H2]=1.5. The relative reactivity with H2 was in an order of Rb(7S)>Rb(5D).
将铷蒸汽与氢气或氦气混合，在玻璃荧光池中用钇铝石榴石激光泵浦的光学参量振荡器（OPO）激光脉冲进行辐照，通过双光子吸收使铷原子跃迁到5D或7S态。利用原子荧光方法测定了与氦原子和氢分子碰撞引起的5D-7S转移截面的温度依赖性。所产生的荧光包括光学激发态衰变时发射的直接成分和碰撞填充态产生的敏化成分。在不同密度下，作者测量了各成分的相对时间积分强度，并拟合了一个三态速率方程模型，以获得铷（7S-5D）与氢气、氦气碰撞的反应性和非反应性截面。铷（7S）+氢气→铷（5D）+氢气的转移截面随温度升高而减小。5D→7S的截面随温度升高而增大。在不同温度下，铷（7S-5D）与氦气碰撞的转移截面符合细致平衡原理。氦气从7S或5D态的总转移速率系数较小。氢气从7S或5D态的总猝灭速率系数要大得多。对于氢气，猝灭速率系数对应于反应和非反应能量转移。在铷（7S，5D）+氢气→氢化铷+H的反应中，发现反应截面之比为σ- [铷（7S）+氢气]/σ-（铷（5D）+氢气]=1.5。铷与氢气的相对反应活性顺序为铷（7S）>铷（5D）。
