Thermal Diffusivity Measurements in Minimal Volume Photoacoustic Cell Using Simple Signal Normalization Techniques

摘要

A self-normalized photothermal technique is used in order to perform thermal diffusivity measurements of condensed phase materials from a minimal-volume photoacoustic (PA) cell. This simple methodology is based on the measurement of the PA signal amplitude as a function of the modulation frequency in the region where the sample is thermally thick. This procedure, which leads to the elimination of the usual requirement for instrumental transfer function normalization and a careful choice of experimental conditions, allows a simple determination of thermal diffusivity in the low frequency range where the thermal diffusion model accounts very well for our data. The thermal diffusivities of four materials, mica, polyvinylidene difluoride (PVDF), the Estar thick base of Kodak's Tri-X films, and slate, were measured and an excellent agreement was obtained with values reported in the literature.