Laser-induced photoacoustic detection of ozone at 266 nm using resonant cells of different configuration

Abstract

A highly sensitive pulsed photoacoustic (PA) spectrometer with different PA cell geometries was designed and fabricated in our laboratory to determine ozone detection at ppb level. The comparative performance and merits of these custom made cells were studied. The excitation source of PA spectrometer is a nanosecond pulsed laser at 266 nm (fourth harmonic of Nd:YAG laser) and a sensitive electret microphone as a photoacoustic detector. The sensitivity optimization of the PA system with different experimental parameters including the resonant acoustic modes of the 3 PA cells was carried out for the detection of ozone. The minimum detection limit for ozone achieved under our experimental conditions, with 3 PA cells were 10, 31 and 26 ppbV for cells designated as cell # 1, cell # 2 and cell # 3, respectively. This limit of ozone detection achieved in our work is quite appreciable to be able to detect ozone under safe permissible limits and the sensitivity achieved in our case is an order of magnitude better than earlier reports using sophisticated laser system like quantum cascade laser.

Keywords:

• Ozone detection
• ozone sensor
• laser photoacoustic spectroscopy
• trace gas analysis
• pollution monitoring

Acknowledgments

The support by the Physics Departments and King Fahd University of Petroleum and Minerals under SABIC project # Sabic 2005/11 is gratefully acknowledged.

Notes

^a With Nitrogen as a buffer gas.

^b 300 ppmV of ozone buffered in 1000 mbar nitrogen at 12 mJ pulse energy.