has participant photoacoustic spectroscopy infrared photoacoustic spectroscopy IR photoacoustic spectroscopy Spectroscopy where the sound emitted when a gaseous sample is exposed to an intense infrared laser beam, which is rapidly interrupted by a rotating slotted disk, is measured. IR optoacoustic spectroscopy IR photoacoustic spectrometry infra-red optoacoustic spectrometry infrared photoacoustic spectrometry IR OAS infrared optoacoustic spectroscopy infra-red photoacoustic spectrometry IR PAS IROAS FIX:0000661 IR optoacoustic spectrometry IRPAS infra-red photoacoustic spectroscopy IR-PAS IR-OAS infrared optoacoustic spectrometry CHMO:0000620 infrared photoacoustic spectroscopy slotted disc