Photoacoustic Investigation of Pesticides

The photoacoustic effect caused by the absorption of the modulated radiation thereby leading to the generation of sound in the gas at the very same chopping frequency, has emerged as a valuable tool for a variety of applications. This is described in several excellent books and review articles on this topic [1,2,3,4,5]. The magnitude of the photoacoustic signal is directly proportional to the amount of the power absorbed by the gas and the concentration of the absorbing species. Throughout recent years frequent studies of atmospheric pollution using the photoacoustic effect in molecular gases in the infrared have been carried out with laser sources [6,7,8,9,10,11]. For a majority of gases, sub part per billion detection sensitivity limits for concentration have been reached with optimized cell designs under realistic atmospheric conditions.