Studies on the theory and applications of the photoacoustic phase of solidsample

Based on the R-G theory of the photoacoustic effect, a new formula on the P A phase was presented while the phase caused by non-radiative relaxation pr ocesses was considered. The phase is associated with the absorption coeffic ient(beta), thermal diffusion length of sample(mu(s)), the delay time of re laxation(tau) and the ratio of the heat component(R) of rapid relaxation to that of slow one. The phase spectra of PrF3 and chlorophyll b were explain ed well by using of this formula. The phase of PrF3 is determined by the ab sorption coefficient for the f-f transition. The phase difference between t he two bands of chlorophyll b is caused by the different heat component rat ios of rapid relaxation to slow one.