Photoacoustic investigations of thermally thin copper phthalocyanine sublimates on quartz were made in wide optical absorption range to verify the validity of the Rosencwaig-Gersho (RG) theory. As could be shown experimentally, both the dependence of the photoacoustic signal on the modulation frequency as well as the constancy of the photoacoustic phase angle spectra agree very well with the theoretical predictions of the RG theory. An additional exponential damping factor has to be taken into account, however, when describing the normalized photosoustic signal as a function of the absorbance. The Influence of the photoacoustic saturation effect on the normalized photoscoustic spectra is discussed.
A. Holter and H.-H. Perkampus, "Photoacoustic Investigations of Thermally Thin Sublimates," Appl. Spectrosc. 39, 278-282 (1985)