infrared photoacoustic spectroscopy Fourier transform infrared photoacoustic spectroscopy FT-IR optoacoustic spectrometry CHMO:0000621 FTIR-PAS FTIR PAS Fourier transform infra-red photoacoustic spectroscopy FTIR OAS FT-IR photoacoustic spectroscopy FTIRPAS Infrared photoacoustic spectroscopy where the spectrum is then subject to a Fourier transform. FTIROAS FT-IR PAS FT-IR OAS FT/IR PAS FT-IR photoacoustic spectrometry FT/IR OAS FT-IR optoacoustic spectroscopy FTIR-OAS