Infrared Spectra of Massive Solids by Photoacoustic Beam Deflection Fourier Transform Spectroscopy

Since the revival of interest in the photoacoustic effect with solids, prompted by Rosencwaig's work,1 most papers dealing with the analytical applications of photoacoustic spectroscopy (PAS) have mentioned and even strongly stressed that one of the advantages of PAS is that sample preparation is not difficult. Such statements are, of course, generally true. What is usually done is to place the substance into a minimum-volume, non-resonant cell; the spectrum is then recorded. “Sample preparation” is thus minimal. However, with solids which are larger than the cavity of the sample cell, which usually is made as small as is feasible in order to increase the photoacoustic signal, such a procedure means that, literally, a sample has to be removed from the solid.