利用简并受激超拉曼泵浦激发HBr(Χ1Σ+ ν″=5)振动态, 由高分辨瞬时激光感应荧光(LIF)探测碰撞弛豫后HBr(ν″≤5)各振动态时间分辨布居数的演化过程, 得到了HBr(ν″=5)分别与分子M(H2, N2, CO2和HBr)的碰撞弛豫速率系数。 对于M=CO2, 近共振的1-1振动-振动(V-V)能量转移是有效的, 这一结果表明CO2强的红外振动模对近共振V-V能量转移是有利的。 而红外禁戒跃迁的N2(0-1)的近共振V-V转移虽然也能观察到, 但相应速率系数比CO2小2个量级。 碰撞分子的振动跃迁红外活性越强, 能量转移速率系数越大。 在HBr(ν″=5)+HBr的自弛豫过程中, 单量子弛豫率占总弛豫率的70%, 而双量子弛豫约占25%。 在HBr(ν″=5)+H2中, 只有2-1的V-V近共振过程是重要的。 同时还研究了V-V近共振能量转移速率系数与温度变化的关系, 对于CO2的1-1近共振, V-V能量转移速率系数随温度的增加而减小; 对于H2和HBr, 其弛豫速率系数随温度的增加而增加; 对于N2, 其弛豫速率系数随温度的增加而缓慢增加。

Collisional deactivation rate constants, k5(M) for HBr(Χ1Σ+ ν″=5) by M= H2, N2, CO2, and HBr were obtained using the degenerated stimulated hyper-Raman (OSHR) pumping method in a pumping-probe configuration. High- resolution transient laser induced fluorescence (LIF) was used to detect collisionally relaxed HBr. For M=CO2, an efficient near-resonant 1-1 vibration-to- vibration (V-V) energy exchange was observed. It appeared that the presence of a strong infrared-active vibrational mode was a favorable situation for an efficient V-V energy transfer. A 1-1 resonance exciting the infrared forbidden N2(1←0) vibration was also observed, but it was 2 orders of magnitude smaller than that of CO2. Self-relaxation rate constants of HBr (ν″=5) were measured. Single quantum relaxation accounted for about 70% of the total relaxation out of state ν″=5, and two-quantum relaxation made contributions (25%) to the vibrational relaxation at this vibrational energy. Direct evidence for 2-1 resonance in HBr (ν″=5)+H2 was observed. Initial preparation of HBr (ν″=5) resulted in nearly no population in HBr (ν″=4), but direct population of HBr (ν″=3). Therefore only 2-1 resonant energy transfer was important for H2 relaxation. The state specific rate constant for HBr was obtained by the analysis of the state-to-state relaxation data. It was found that the data could be fitted with one adjustable normaligation parameter using a single-quantum relaxation model, which restricted the rate constant. A strong mass effect on the vibrational relaxation rate constant was observed. A further check of the character of the V-V resonant energy transfer in highly vibrationally excited HBr was the temperature dependence of the rate constants. For M=CO2, the temperature dependence of the 1-1 near-resonant energy transfer rate constats was found to be inverted. In contranst, the temperature dependence of the relaxation rate constants for M= H2 and HBr was normal. For M=N2, a weak but position temperature dependence was found. It suggested that this resonance occurred by a different mechanism compared with that in CO2.