Differential mode excitation photoacoustic spectroscopy: a new photoacoustic detection scheme.
A robust and simple gas sensor based on a novel photoacoustic scheme named "differential mode excitation photoacoustic spectroscopy (DME-PAS)" is presented. This method takes advantage of the selective excitation of two different modes in a resonant photoacoustic cell. A blackbody light source is used for simplicity in combination with optical correlation to provide a good selectivity. The frequency response of the proposed resonant cell is modeled using the extended Helmholtz resonator theory. The DME-PAS device is tested using acetone vapor and a model developed to describe its response when the gas concentration is varied. The obtained limit of detection is 25 ppm m(-1) for acetone in room air. Using DME-PAS, the derived gas concentration is affected neither by intensity fluctuations of the light source nor by any microphone drifts.
Rey
J M
JM
Laser Spectroscopy and Sensing Laboratory, Institute of Quantum Electronics, ETH Zurich, Schafmattstrasse 16, CH-8093 Zurich, Switzerland.
Sigrist
M W
MW
D000162:Acoustics / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis*; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods
D005740:Gases