Optical Gas-Cell Dynamic Adsorption in a Photoacoustic Spectroscopy-Based SOF2 and SO2F2 Gas Sensor

Abstract

SO2F2 and SOF2 are the main components from the decomposition of insulation gas SF6. Photoacoustic spectroscopy (PAS) has been acknowledged as an accurate sensing technique. Polar material adsorption for SO2F2 and SOF2 in the photoacoustic gas cell of PAS may affect detection efficiency. In this paper, the optical gas-cell dynamic adsorptions of four different materials and the detection effects on SO2F2 and SOF2 are theoretically analyzed and experimentally demonstrated. The materials, including grade 304 stainless steel (SUS304), grade 6061 aluminum alloy (Al6061), polyvinylidene difluoride (PVDC), and polytetrafluoroethylene (PTFE), were applied inside the optical gas cell. The results show that, compared with metallic SUS304 and Al6061, plastic PVDC and PTFE would reduce the gas adsorption of SO2F2 and SOF2 by 10 to 20% and shorten the response time during gas exchange. The complete gas defusing period in the experiment was about 30 s. The maximum variations of the 90% rising time between the different adsorption materials were approximately 3 s for SO2F2 and 6 s for SOF2, while the generated photoacoustic magnitudes were identical. This paper explored the material selection for PAS-based gas sensing in practical applications.

Detection of SO2F2 Using a Photoacoustic Two-Chamber Approach

“…Generally, resonant devices can achieve such low detection limits, but they are much more complex and expensive than non-resonant sensors. Resonant photoacoustic sensors have already been proposed for SO 2 F 2 sensing but are restricted to laboratory use [ 24 , 25 , 26 , 27 , 28 ]. If the modulation of the light source is operated at a frequency that is much smaller than the smallest resonance frequency of the photoacoustic cell (PA) cell, this is referred to as non-resonant operation.…”