A photoacoustic spectroscopy measurement of near-infrared low-mass multi-component gas at room temperature and atmospheric pressure

Abstract

Under normal temperature and pressure, intensive overlaps of measured gas absorption lines due to pressure broadening in near infrared (NIR) band lead to a puzzle of the resolution of the measured signal of multi-component photoacoustic spectroscopy (PAS) in a trace gas detection. In this paper, super-Gauss distribution characteristics of NIR and low-mass spectrum at room temperature and pressure are analyzed and demonstrated. A multiple gas PAS sample with the super-Gauss distribution can be regarded as a sum of feature absorptions weighted by the spacing between adjacent feature wavelengths. Several expected feature gases with super-Gauss distribution are simultaneously extracted out from the experimental PAS samples by FastICA algorithm, which was proposed in our former research (‘Feature extraction for gas photoacoustic spectroscopy and content inverse based on overcomplete ICA bases’ published in Optics & Laser Technology). The FastICA algorithm is re-proposed and re-tested within a very limited scanning PAS band. With no exception, the theoretical proof and analyzed cases as well as the test result accord with the gas information of many components from actual overcomplete-ICA basis PAS sample and with super-Gauss distribution which can be extracted in a very limited spectrum (e.g., 0.15 nm in this study) in room temperature and pressure.