Phototermal Spectra of Inhomogeneous Coatings

Abstract

In this paper we demonstrate a theoretical study for photothermal measurements on inhomogeneous coatings. First, a general photothermal mathematical model for thermal gradient materials is presented. Then, we discuss the effects of inhomogeneous thermal properties in photothermal amplitude and phase spectra of coatings. Finally, a method for quantitative depth profiling that makes use of prior knowledge about the type of profile existing in a sample to reduce the instabilities associated with the mathematically ill conditioned task is demonstrated.

Influence of non-irradiated surface optical absorber on temperature gradient induced by photothermal effect in a thin film

“…Photothermal (PT), and consequently photoacoustic (PA) techniques, are based on direct or indirect measurement of phenomena resulting from heat transfer processes in the examined material, whereas the most straightforward approach considers the examination of surface temperature variations of the sample (Popovic et al, 2018(Popovic et al, , 2021. Since these experimental techniques are considered model-dependent, their development largely involves the development and the analysis of theoretical-mathematical models which link physical processes in the examined material and the measured signal (Dramićanin et al, 2000;Galovic et al, , 2014Galović and Dramićanin, 1999;Markushev et al, 2019;Nesic et al, 2016;Nesic, Galovic, et al, 2012;Nesic, Gusavac, et al, 2012;Popovic et al, 2021) (Aleksić et al, 2022;Djordjevic et al, 2022;Markushev et al, 2018Markushev et al, , 2020Popovic et al, 2009;Somer et al, 2013;Soskic et al, 2012Soskic et al, , 2016Todorović, 2003;Todorović and Nikolic, 2000).…”