Photoacoustic Detection of Carbonaceous Atmospheric Aerosols

The role of carbonaceous aerosols in the atmosphere as a risk factor in climatic changes and health effects and state-of-the-art monitoring processes are briefly presented here. In particular, development of a photoacoustic technique for measuring the concentration of carbonaceous particles is discussed. The photoacoustic measurement is based upon detection of pressure waves generated by localized time-dependent heating of air inside the photoacoustic chamber. Heating of air inside the chamber is due to absorption of visible laser radiation by carbon particles present inside the chamber. The laser radiation is chopped, and the resultant pressure signal produced by subsequent heating and cooling of the gas is monitored using a microphone. Sensitivity of this photoacoustic technique and its application is monitoring soot particles in the atmosphere is discussed