PHOTOACOUSTIC PHASE SPECTRUM OF A LAYERED SAMPLE

Based on the Rosencwaig-Gersho theory (RG), we have studied the PhotoA coustic Phase Spectrum (PAPS) of a two-layer sample. The theoretical r esults are mainly verified by an experiment, in which an intact plant leaf is used as the sample. The ratio of the optical absorption coeffi cient to the thermal diffusion coefficient for the subsurface layer ca n be obtained from the theoretical formula using measured phase values . The spectrum formed by the ratios at different wavelengths is in a g ood agreement with those experimentally obtained by phaseresolved phot oacoustic spectroscopy.