The contribution of temperature dependence of optical absorption coefficient of the sample to the formation of a thermal field in a photoacoustic cell

Abstract

Expressions describing the peculiarities of the temperature field formation in the photoacoustic cell, taking into account the temperature dependence of not only the thermophysical parameters of all layers and the absorptivity, but also of the optical absorption coefficient of the sample have been obtained. A system of nonlinear algebraic equations has been derived to determine the dependence of temperatures of the illuminated layer of the sample and its reverse side on the intensity of the incident beam. As a result of numerical solution of this system, nonlinear dependences of temperatures of both sides of the sample on the beam intensity have been obtained. The sign of the thermal coefficient of the temperature dependence of the optical absorption coefficient has been found to significantly affect the nature of the dependences of the increment of the irradiated surface temperature and the rear side of the sample on the intensity. Significant effect of the substrate on the formation of the temperature field in the photoacoustic cell has been shown as well.