Impulsive stimulated light scattering. I. General theory

Abstract

Theoretical analysis of the time-resolved impulsive stimulated light scattering (ISS) method is presented. A general theoretical framework is developed to describe ISS experiments on any type of material mode which is active in light scattering and conforms to linear response theory. ISS experiments permit time-resolved observation of material motion through the dielectric response function Gεε(q,t). In the simplest case of ideal time and wave vector resolution, ISS signal gives ‖Gεε(q,t)‖2 directly. Various consequences of limited t and q resolution are discussed in detail. ISS experiments on acoustic and optic phonons, Debye relaxational modes, and some combinations of modes are treated explicitly. A detailed comparison of time-domain impulsive stimulated scattering and frequency-domain spontaneous light-scattering spectroscopy is presented in the companion paper.