A study of the photoacoustic effect in ethylene gas

Jay Nguyen, University of Tennessee at Chattanooga

Dept. of Chemistry


Ethylene, C2H4, is a plant hormone produced and released naturally by plants and soil microorganisms. This colorless, flammable gas has a slightly sweet odor usually only recognized by those who have handled ethylene before. In situ analyses of this gas and many other potentially harmful gases outside of the laboratory are often difficult to perform due to the lack of a portable yet reliable unit capable of precisely and accurately detecting and measuring the concentrations of these gases at trace gas concentrations of a few parts per billion. In this research project, photoacoustic spectroscopy was used to detect and measure the concentration of ethylene. Multiple aspects of the experimental setup were independently manipulated to determine each of their effects on the photoacoustic behavior exhibited. The data obtained in this research project was used to help formulate a discussion about what experimental conditions were most ideal for detection and measurement of ethylene using photoacoustic spectroscopy. It was determined that this technique was most reliable when the internal radius of the cavity resonator was small, the power of the light source was high, the concentration of ethylene gas was high, and the rotational frequency of the mechanical chopper was low. These experimental conditions should be considered by manufacturers when devising highly-sensitive, low-cost portable systems for the detection and measurement of ethylene gas both inside and outside the laboratory.