Quantitative Evaluation of Broadband Photoacoustic Spectroscopy in the Infrared with an Optical Parametric Oscillator

We evaluate the spectral resolution and the detection thresholds achievable for a photoacoustic spectroscopy (PAS) system in the broadband infrared wavelength region [Formula: see text] driven by a continuous wave optical parametric oscillator (OPO) with [Formula: see text]. The absorption spectra, [Formula: see text] , for diluted propane, ethane and methane test gases at low concentrations ([Formula: see text]) were measured for ∼1350 discrete wavelengths [Formula: see text]. The [Formula: see text] spectra were then compared to the high resolution cross section data, [Formula: see text] , obtained by Fourier Transform Infrared Spectroscopy published in the HITRAN database. Deviations of 7.1(6)% for propane, 8.7(11)% for ethane and 15.0(14)% for methane with regard to the average uncertainty between [Formula: see text] and the expected reference values based on [Formula: see text] were recorded. The characteristic absorption wavelengths [Formula: see text] can be resolved with an average resolution of [Formula: see text]. Detection limits range between [Formula: see text] ppb (ethane) to [Formula: see text] ppb (methane). In an additional step, EUREQA, an artificial intelligence (AI) program, was successfully applied to deconvolute simulated PAS spectra of mixed gas samples at low limits of detection. The results justify a further development of PAS technology to support e.g., biomedical research.