Quartz-enhanced photoacoustic spectroscopy for CO detection in SF6 decomposition

We report on a highly sensitive and selective optical sensor for detection of carbon monoxide (CO) in a sulfur hexafluoride (SF6) gas matrix by using quartz-enhanced photoacoustic spectroscopy (QEPAS) technique. The sensor uses a mid-infrared quantum cascade laser with central wavelength at 4.61 μm as light source and a spectrophone consisting of a novel 8 kHz T-shaped quartz tuning fork with grooved prongs coupled with a pair of resonator tubes for photoacoustic detection. A minimum detection limit of 10 ppb at 10 s of signal integration time was achieved.