Fluorescence spectra and lifetimes of anisole and toluene vapor in nitrogen have been measured at conditions below ambient (257–293 K and 100–2000 mbar) upon excitation with 266-nm laser light to expand the applicable range of anisole and toluene laser-induced fluorescence (LIF) for conditions below room temperature that occur in expanding flows and cases with strong evaporative cooling. Anisole fluorescence spectra broaden with decreasing pressure while fluorescence lifetimes decrease simultaneously. This is consistent with a more pronounced effect of internal vibrational redistribution on the overall fluorescence signal and can be explained by significantly reduced collision rates. In the case of toluene, the transition from photo-induced heating to photo-induced cooling was observed for the first time for 266 nm. The data confirm predictions of earlier work and is particularly important for the advancement of the available photo-physical (step-ladder) models: since those transitions mark points where the molecules are already thermalized after excitation (i.e., no vibrational relaxation occurs during deactivation), they are important support points for fitting empirical parameters and allow analytical determination of the ground state energy transferred to the excited state. The data enable temperature and/or pressure sensing, e.g., in accelerating cold flows using laser-induced fluorescence of both tracers.

在266 nm激光激发下，在低于环境温度（257–293 K和100–2000 mbar）的条件下，测量了氮气中苯甲醚和甲苯蒸气的荧光光谱和寿命，从而扩展了苯甲醚和甲苯激光诱导的荧光的适用范围（LIF）适用于在膨胀气流中发生的低于室温的条件以及具有强力蒸发冷却的情况。茴香醚荧光光谱随着压力的降低而变宽，而荧光寿命同时降低。这与内部振动重新分布对整个荧光信号的更明显影响相一致，并且可以通过显着降低的碰撞率来解释。对于甲苯，在266 nm处首次观察到从光致加热到光致冷却的转变。数据证实了对较早工作的预测，并且对于可用光物理（阶梯）模型的发展特别重要：因为这些跃迁标记了激发后分子已经热化的点（即在钝化过程中没有发生振动弛豫） ，它们是拟合经验参数的重要支持点，并允许分析确定传递给激发态的基态能量。该数据可实现温度和/或压力感测，例如，在使用两个示踪剂的激光诱导荧光加速冷流的过程中。在停用期间不会发生振动弛豫），它们是拟合经验参数的重要支撑点，并且可以分析确定传递给激发态的基态能量。该数据可实现温度和/或压力感测，例如，在使用两个示踪剂的激光诱导荧光加速冷流的过程中。在停用期间不会发生振动弛豫），它们是拟合经验参数的重要支撑点，并且可以分析确定传递给激发态的基态能量。该数据可实现温度和/或压力感测，例如，在使用两个示踪剂的激光诱导荧光加速冷流的过程中。