用增强型光声池显著降低了光声信号的面损耗,使得AsH3分子的振动平动能量转移成为造成共振峰展宽的主要因素。光声池内充9.06 kPa的AsH3气体,声共振品质因子Q高达374。推导了光声信号振幅与入射光调制频率和样品分子振动－平动弛豫时间的函数关系。理论公式与实验数据的对比表明,对振动热容贡献大的振动能级在气体分子的振动平动能量转移过程中起主要作用;波动过程中AsH3分子通过最低的两个振动能级进行振动平动能量交换。

With an enhanced photoacoustic cell, the surface loss of the cell is decreased obviously, thus the resonant peak broadening is mainly due to the vibrational-translational (V-T) relaxation of AsH3. The high quality factor Q value of 374 has been achieved for AsH3 gas at the pressure of 9.06 kPa. An expression for acoustic wave amplitude as a function of modulation frequency and relaxation time has been derived. This theoretical formula is fitted to the experimental data, then the relaxation process of AsH3 is studied . The results reveal that the V-T energy transfer of gas molecules is determined mainly by the molecules′ vibrational states, which contribute the most to the vibrational heat capacity; and the two-energy level double relaxation process is the most possible process for the vibrational-translation energy transfer for AsH3.