Water and D₂O have distinct spectral densities resulting from isotopic shifts associated with their vibrational manifold. Two-dimensional infrared, pump–probe, and transient grating spectroscopies were employed to directly measure the vibrational dynamics for the azide transition of NaN₃ within solutions of water and D₂O. Although the frequency correlation time revealed minimal variation, a linear correlation between lifetime and the optical density of the solvent background was uncovered. Thus, a predictive model of the lifetime was proposed. These findings highlight the importance of spectral density of the solvent and its role in the pathways of energy dissipation for vibrational probes.

水和D ₂ O由于与其振动流形相关的同位素位移而具有不同的光谱密度。采用二维红外、泵浦探针和瞬态光栅光谱直接测量水和 D ₂ O溶液中NaN ₃叠氮化物跃迁的振动动力学。虽然频率​​相关时间显示出最小的变化，但揭示了寿命和溶剂背景光密度之间的线性相关性。因此，提出了寿命的预测模型。这些发现强调了溶剂光谱密度的重要性及其在振动探针能量耗散途径中的作用。