Characterization of Thermal Propel. ..: of Matter by Photoacoustic and Photothermal Techniques

Abstract

Photothermal spectroscopies are powerful techniques for measuring optical and thermal properties of solid samples, through detection of heat generated within the sample by nonradiative relaxation process. Among the better known . examples of these spectroscopies are photothermal deflection spectroscopy (PDS) and photoacoustic spectroscopy (PAS). Both spectroscopies measure the heat generated in the materials due to absorption of photons either optically in the case of PDS or acoustically in the case of PAS. The PDS is based on the sensitive detection of thermal gradient adjacent to the heated sample surface, while the basic idea of PAS is the production of acoustic signal from a sample in a closed cell containing gas (air) and a sensitive microphone when it is illuminated with a chopped light.