Photoacoustic Measurements of Agriculturally Interesting Gases and Detection of C₂H₄ below the PPB Level

Abstract

We present a laser photoacoustic system which is able to detect a minimum absorption coefficient of 7.1 × 10 −10 cm −1 corresponding to a concentration of 20 parts per trillion of C 2 H 4 in air. Improvements made to achieve this sensitivity are reported, and this low limit is applied to the detection of the C 2 H 4 emission of a single orchid flower after emasculation. In addition, the absorption coefficients and detection limits of the following agriculturally interesting gases are measured: ozone, hydrogen sulphide, 1,2 dibromoethane, and ethylacetate.