Pulsed photoacoustic detection of CO2 and C2H4 in infrared region

Abstract

The detection of air pollutants in the atmosphere is of interest both from the physical point of view and from the atmospheric environmental aspect. Air pollutants are monitored by gas chromatograph techniques or, with better detection limits, by photoacoustic spectroscopy (PAS). The sensitivity of infrared (IR) photoacoustic (PA) detectors is limited not only by the magnitude of the background signal, but also depends on the gas constituents. The presence of CO2 gas in gas samples leads to the decrease of the amplitude of the detected PA signal, due to the effect of the kinetic cooling. Only few IR gas-phase PAS investigations have been made with pulsed CO2 laser sources.1,2