Photoacoustic methodologies for thermal diffusivity measurements for highly opaque single-layered materials

The analytical solution for the one-dimensional heat diffusion problem, involving a harmonic heat source in a single layer, is used to provide of photoacoustic self-normalized methodologies for thermal diffusivity measurements for highly opaque materials. The self-normalized procedure involves the photoacoustic phase lag between the rear and front configurations. Three methodologies are described; two of them involving linear fits in the photoacoustic thermally thick and thermally thin regimes. Comparison between the theoretical normalized equations and the corresponding normalized experimental data allows for the development of criteria on the selection of an appropriate modulation frequency range where a reliable analysis can be done.