Dependence of the Photoacoustic Cell Constant on the Sample Gas

The CO2 laser and the windowless resonant cell equipped with the electronic resonance tracking system were combined into the photoacoustic spectrometer. In order to facilitate the comparison of various analytical purpose PA systems and other spectroscopic methods, we suggest the introduction of instrumental figure characterizing the PA instrument. The photoacoustic spectrometer was calibrated using a series of certified precision mixtures of ammonia, ethylene and carbon-dioxide in a high purity grade nitrogen. The absorbance as low as 2*10−6 could be measured. The instrumental figures were found different: 0.98 V/W for the carbon-dioxide, 1.68 V/W for ethylene and 2.4 V/W for the ammonia.