Self-normalized photothermal technique for accurate thermal diffusivity measurements in thin metal layers

A self-normalized photothermal method for measuring thermal diffusivity of thin metal layers has been implemented using two experimental configurations based on photothermal radiometry and gas-cell photoacoustic detection. The corresponding measurement procedures involve linear fits in the photothermally thin and/or thick limits. As part of this method, simple experimental criteria have been developed to ascertain that a purely thermal-diffusion-wave mechanism is dominant throughout the selected frequency range, thus validating the accuracy of the thermal diffusivity measurements. Thermal-diffusivity values measured using the intrinsic reliability of this self-normalized photothermal measurement scheme are reported for two commercial samples of aluminum and steel thin layers.