Generation of a Photoacoustic Signal in Two-Layer Transparent Samples on an Absorbing Substrate

Abstract

A theory of generation of a photoacoustic signal in a two-layer transparent sample on an absorbing substrate to a buffer gas of a photoacoustic cell has been developed. We have shown that the frequency dependence of the photoacoustic signal amplitude excited in the absorbing substrate obeys the law ∝ ω^–1, when a free path of photons is less than the thermal diffusion length, and is proportional to ω^–3/2 in the opposite case.