Impulsive stimulated light scattering. II. Comparison to frequency-domain light-scattering spectroscopy

Abstract

A comparison between time‐domain impulsive stimulated light‐scattering (ISS) and frequency‐domain, spontaneous light‐scattering (LS) spectroscopies is carried out in theoretical and practical terms. In some cases, the two experiments probe different material responses. In many cases the information content of ISS and LS data is identical in principle. The results can be related to each other through the time‐ and frequency‐dependent response functions G εε(q,t) and G εε(q,ω), or through the time‐correlation function C εε(q,t). Simulated ISS and LS data from vibrational and Debye relaxational modes are compared in view of experimental considerations, including wave vector and time or frequency resolution and range, and sources of ‘‘noise.’’ In many cases, one or the other experimental approache offers significant advantages in practice. The complementary nature of the techniques is illustrated.