TY - JOUR A1 - Zifarelli, Andrea A1 - Cantatore, Aldo Francesco Pio A1 - Sampaolo, Angelo A1 - Mueller, Max A1 - Rueck, Thomas A1 - Hoelzl, Christine A1 - Rossmadl, Hubert A1 - Patimisco, Pietro A1 - Spagnolo, Vincenzo T1 - Multivariate analysis and digital twin modelling: Alternative approaches to evaluate molecular relaxation in photoacoustic spectroscopy JF - Photoacoustics N2 - A comparative analysis of two different approaches developed to deal with molecular relaxation in photoacoustic spectroscopy is here reported. The first method employs a statistical analysis based on partial least squares regression, while the second method relies on the development of a digital twin of the photoacoustic sensor based on the theoretical modelling of the occurring relaxations. Methane detection within a gas matrix of synthetic air with variable humidity level is selected as case study. An interband cascade laser emitting at 3.345 µm is used to target methane absorption features. Two methane concentration ranges are explored targeting different absorptions, one in the order of part-per-million and one in the order of percent, while water vapor absolute concentration was varied from 0.3 % up to 2 %. The results achieved employing the detection techniques demonstrated the possibility to efficiently retrieve the target gas concentrations with accuracy > 95 % even in the case of strong influence of relaxation effects. KW - digital twin model KW - methane detection over a wide concentration range KW - multivariate analysis KW - Partial Least Squares Regression KW - QEPAS sensor KW - relaxation effects photoacoustic spectroscopy KW - water vapor influence on relaxation Y1 - 2023 U6 - https://doi.org/10.1016/j.pacs.2023.100564 SN - 2213-5979 VL - 33 PB - Elsevier ER -