The possibility of using a minimal-volume photoacoustic cell to perform spectroscopy of samples is discussed. It is shown that this alternative signal-to-noise-enhanced photoacoustic configuration allows one to obtain both absorption and transmission spectra with minimal experimental arrangement and cell machining requirements. The theoretical model is presented, the use of which is exemplified by a complete optical and thermal characterization of leaves.

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The photoacoustic measurement of polymer foils, typically 170--200 pm thick, is discussed. It is shown that the measurement based upon the phase lag between the front and rear illuminations is applicable only in a limited range offrequencies from 6 to 12 Hz. The dominant mechanism responsible for the photoacoustic signal, in almost the entire frequency range 10-100 Hz, is proven to be the thermoelastic bending of the foil samples. The thermal diffusivity is then obtained from the frequency dependence of the front~phase illumination data.

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