Theoretical analysis of pulse photoacoustic effect in gas filled cell

Pulse photoacoustic effect in solids is a foundation of nondestructive data acquisition method describing thermal properties of solid samples. Pulse research may be carried out using facilities developed for photoacoustic, continuous wave investigation, but proper interpretation of results obtained in a particular experimental setup requires that a theoretical model be developed. In this paper a one-dimensional model of four-segment photoacoustic cell consisting of backing, sample, gas, and window is described. Laser pulse passes through non-absorbing window and gas, and is absorbed in the sample that gives up the heat to the surrounding: backing, gas, and window. Due to thermodynamic process the gas changes its pressure what may be recorded with a microphone. The model is based on analytical general solutions of parabolic heat diffusion equations for each area, with boundary conditions of the 4th type at material interfaces.