Photoacoustic detection of circular dichroism

An analysis is presented for an experimental technique involving the measurement of circular dichroism using polarization-modulated photoacoustic spectroscopy. The technique is referred to as photoacoustic circular dichroism (PACD). In the PACD experiment, a photoacoustic signal is induced by using polarization-modulated excitation light which is alternately left-and right-circularly polarized. Expression appropriate for analyzing the PACD experimental observables (signal strength and phase) in terms of sample circular dichroism are developed within the general framework of the Rosencwaig and Gersho model for the photoacoustic effect in solids and liquids. Calculations based on these expressions are reported and the applicability of PACD for measuring the circular dichronic properties of optically opaque samples is discussed.