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

Autor: Yannick Saalberg, Marcus Wolff, K. M. Spohr, Henry Bruhns
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: Sensors
Volume 18
Issue 11
Sensors (Basel, Switzerland)
Sensors, Vol 18, Iss 11, p 3971 (2018)
ISSN: 1424-8220
DOI: 10.3390/s18113971
Popis: We evaluate the spectral resolution and the detection thresholds achievable for a photoacoustic spectroscopy (PAS) system in the broadband infrared wavelength region 3270 n m ≲ &lambda
≲ 3530 n m driven by a continuous wave optical parametric oscillator (OPO) with P ¯
&asymp
1.26 W . The absorption spectra, I PAS ( &lambda
i ) , for diluted propane, ethane and methane test gases at low concentrations ( c &sim
100 ppm ) were measured for &sim
1350 discrete wavelengths &lambda
i . The I PAS ( &lambda
i ) spectra were then compared to the high resolution cross section data, &sigma
FTIR , 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 I PAS ( &lambda
i ) and the expected reference values based on &sigma
FTIR were recorded. The characteristic absorption wavelengths &lambda
res can be resolved with an average resolution of &delta
&lambda
res &sim
0.08 nm . Detection limits range between 7.1 ppb (ethane) to 13.6 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.
Databáze: OpenAIRE
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