H2S quartz-enhanced photoacoustic spectroscopy sensor employing a liquid-nitrogen-cooled THz quantum cascade laser operating in pulsed mode

Angelo Sampaolo; Chenren Yu; Tingting Wei; Andrea Zifarelli; Marilena Giglio; Pietro Patimisco; Huan Zhu; Haiqing Zhu; Li He; Hongpeng Wu; Lei Dong; Gangyi Xu; Vincenzo Spagnolo

doi:10.1016/j.pacs.2020.100219

H₂S quartz-enhanced photoacoustic spectroscopy sensor employing a liquid-nitrogen-cooled THz quantum cascade laser operating in pulsed mode

Photoacoustics. 2020 Dec 9:21:100219. doi: 10.1016/j.pacs.2020.100219. eCollection 2021 Mar.

Authors

Angelo Sampaolo^{1

2}, Chenren Yu³, Tingting Wei¹, Andrea Zifarelli^{1

2}, Marilena Giglio^{1

2}, Pietro Patimisco^{1

2}, Huan Zhu³, Haiqing Zhu³, Li He³, Hongpeng Wu¹, Lei Dong¹, Gangyi Xu³, Vincenzo Spagnolo^{1

2}

Affiliations

¹ State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy & Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006, China.
² PolySense Lab, Dipartimento Interateneo di Fisica, University and Politecnico of Bari, CNR-IFN, Via Amendola 173, Bari, 70126 Italy.
³ Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China.

Abstract

In this work, we report on a quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor for hydrogen sulfide (H₂S) detection, exploiting a liquid-nitrogen-cooled THz quantum cascade laser (QCL) operating in pulsed mode. The spectrophone was designed to accommodate a THz QCL beam and consisted of a custom quartz tuning fork with a large prong spacing, coupled with acoustic resonator tubes. The targeted rotational transition falls at 2.87 THz (95.626 cm^-1), with a line-strength of 5.53 $∙$ 10^-20 cm/mol. A THz QCL peak power of 150 mW was measured at a heat sink temperature of 81 K, pulse width of 1 μs and repetition rate of 15.8 kHz. A QEPAS record sensitivity for H₂S detection in the THz range of 360 part-per-billion in volume was achieved at a gas pressure of 60 Torr and 10 s integration time.

Keywords: Gas sensing; H2S; Quantum cascade laser; Quartz enhanced photoacoustic spectroscopy; THz.