DEPENDENCE OF AN ACOUSTICALLY NONRESONANT INTRACAVITY PHOTOACOUSTIC SIGNAL ON SAMPLE AND BUFFER GAS-PRESSURE

The thermodynamic solid-gas theory of Kerr and Atwood is combined with an expression for electret microphone sensitivity to predict the depe ndence of photoacoustic signal strength for a nonresonant cell on heat capacity and sample pressure of a pure gas. We measure the photoacous tic signal dependence on sample pressure for four hydrocarbon gases an d find that the signal increases with pressure but reaches a plateau w hose height varies inversely with C-v, The results are in accord with our simple theoretical analysis. We measure the photoacoustic signal d ependence on added krypton pressure for propane, isobutane, and naphth alene. After an initial increase with increasing krypton pressure, the photoacoustic signal eventually falls off at higher krypton pressures . We discuss the results on the basis of our analysis of a pure gas.