Continuous wave photothermal deflection spectrometry based on Fresnel diffraction theory: Experimental applications

Abstract

Recently we developed a one-dimensional continuous wave photothermal deflection model based on Fresnel diffraction theory with a set of closed-form analytical signal expressions for both fundamental and second harmonic responses. This article reports its experimental applications in thermal property measurements, demonstrating the simplicity, validity, and usefulness of these analytical signal expressions. The thermal diffusivity of air was found to be (2.2±0.1)×10−5 m2/s that is consistent with literature value; the thermal effusivities of a rubber and a graphite plate sample were determined to be (1.2±0.2)×103 W s1/2 m−2 K−1 and (5.6±0.2)×103 W s1/2 m−2 K−1, respectively, which are in good agreement with the measured values of the same samples by a photoacoustic method.