Photoacoustic Measurement of Carbon Monoxide Using a Semiconductor Diode Laser

Abstract

Photoacoustic measurements have been made at the 4.803 μm absorption line of carbon monoxide in a small nonresonant cell using a low power semiconductor laser source. A simple theoretical model correctly predicts the dependence of the CO signal on chopping frequency and concentration dependence but is inadequate in describing the pressure dependence. Concentrations as low as 50 ppmv were measured by operating the cell in a double pass mode.