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 C2H4 in air. Improvements made to achieve this sensitivity are reported, and this low limit is applied to the detection of the C2H4 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.