A theory for time-resolved photothermal spectroscopy is proposed for in situ determination of reaction and phase transformation kinetics and mechanisms in condensed media. The theory is developed from the thermal diffusion equation for thin slabs of materials with a finite optical absorption coefficient undergoing a first-order process. The ratio of the photo-response to the total thermal response is evaluated for various reaction kinetics, and a series of time-resolved spectra is constructed.
J. R. Schoonover and S. H. Lin, "A Model for Time-Resolved Photothermal Spectroscopy of Reactions in Condensed Media," Appl. Spectrosc. 43, 1265-1269 (1989)