The CO₂ Laser Based Photoacoustic Spectrometer And It's Biological Application

Because of its high sensitive and selective characteristics,the photoacoustic spectrometer is regared as one of the best tools for trace gas detection.The paper introduces the historical developments of photoaeoustic spectrometer, the new achievements in recent years,and the main points of the technology. The theory of acoustic resonance standing wave is presented in detail,and we calculate the parameters of photoacoustic cell according to the model. On the basis of the above model,we designed a CO2 laser based photoacoustic spectrometer. In order to study the important modulating effects of ethylene on plants biological activities ,we used this device to measure the concentration of ethylene produced by plants under different conditions.The device抯 minimum detection limit of ethylene reaches 20 ppt,much preciser than the conventional means. A new method could be available to the study of biology and atmosphere pollutants detection when this spectrometer is further developed.