Assessment of vibrational-translational relaxation dynamics of in a wet-nitrogen matrix through QEPAS

Mariagrazia Olivieri; Marilena Giglio; Stefano Dello Russo; Giansergio Menduni; Andrea Zifarelli; Pietro Patimisco; Angelo Sampaolo; Hongpeng Wu; Lei Dong; Vincenzo Spagnolo

doi:10.1016/j.pacs.2023.100518

Assessment of vibrational-translational relaxation dynamics of in a wet-nitrogen matrix through QEPAS

Photoacoustics. 2023 Jun 2:31:100518. doi: 10.1016/j.pacs.2023.100518. eCollection 2023 Jun.

Authors

Affiliations

¹ State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China.
² PolySense Lab - Dipartimento Interateneo di Fisica, Politecnico and University of Bari, Via Amendola 173, Bari, Italy.
³ Italian Space Agency (ASI), Centro di geodesia Spaziale "Giuseppe Colombo", Matera, Italy.

Abstract

Here we report on a study of the non-radiative relaxation dynamic of ¹²CH₄ and ¹³CH₄ in wet nitrogen-based matrixes by using the quartz-enhanced photoacoustic spectroscopy (QEPAS) technique. The dependence of the QEPAS signal on pressure at fixed matrix composition and on H₂O concentration at fixed pressure was investigated. We demonstrated that QEPAS measurements can be used to retrieve both the effective relaxation rate in the matrix, and the V-T relaxation rate associated to collisions with nitrogen and water vapor. No significant differences in measured relaxation rates were observed between the two isotopologues.

Keywords: Methane isotopologues; Quantum cascade laser; Quartz-enhanced photoacoustic spectroscopy; Relaxation rates; Trace gas sensing.