Light scattering effects in photoacoustic spectroscopy

Abstract

The influence of light scattering on photoacoustic signals is treated. Theoretical and experimental results are compared. The theoretical results are based on a model in which the photons diffuse through the sample. An equation governing the diffusion process is solved with appropriate boundary conditions. This gives the distribution of photons in the sample. The photoacoustic signal is then calculated and the result is compared with the result for nonscattering samples, giving the influence of the light scattering. The experimental results are obtained by measuring the photoacoustic signal for both scattering and nonscattering samples. The experimental and theoretical results are in good agreement. The differences are mainly due to the incompleteness of the original diffusion theory. An improved theory incorporating internal reflection at the sample surface is also analyzed. The paper illustrates the effects of light scattering on photoacoustic signals. It also shows how to estimate theoretically the photoacoustic signal from a light-scattering sample.