Optoacoustic Detection with a Helmholtz Resonator: Application to Trace Detection of Carcinogens

The first reports of the use of a laser to produce the optoacoustic effect (1-4) have shown that detection of infrared active gases can be carried out with both high sensitivity (at the sub-part-per-billion level) and high selectivity. Although such characteristics immediately suggest application of this effect as a detection method for gas chromatography, in fact, only a few reports of a laser-optoacoustic detector have appeared. Kreuzer (5) described a small volume, cylindrical absorption cell with an external microphone that was excited at a frequency below the first acoustic resonance. Similarly, Zharov and co-workers (6) have developed a laser-optoacoustic detector for infrared active species. Choi and Diebold (7) have recently reported the application of chemical amplification to detection of a number of species eluting from a gas chromatography column.