THz quartz-enhanced photoacoustic sensor for H₂S trace gas detection.


We report on a quartz-enhanced photoacoustic (QEPAS) gas sensing system for hydrogen sulphide (H₂S) detection. The system architecture is based on a custom quartz tuning fork (QTF) optoacoustic transducer with a novel geometry and a quantum cascade laser (QCL) emitting 1.1 mW at a frequency of 2.913 THz. The QTF operated on the first flexion resonance frequency of 2871 Hz, with a quality factor Q = 17,900 at 20 Torr. The tuning range of the available QCL allowed the excitation of a H₂S rotational absorption line with a line-strength as small as S = 1.13·10⁻²² cm/mol. The measured detection sensitivity is 30 ppm in 3 seconds and 13 ppm for a 30 seconds integration time, which corresponds to a minimum detectable absorption coefficient α(min) = 2.3·10⁻⁷ cm⁻¹ and a normalized noise-equivalent absorption NNEA = 4.4·10⁻¹⁰ W·cm⁻¹·Hz(-1/2), several times lower than the values previously reported for near-IR and mid-IR H₂S QEPAS sensors.

DOI: 10.1364/OE.23.007574

Cite this paper

@article{Spagnolo2015THzQP, title={THz quartz-enhanced photoacoustic sensor for H₂S trace gas detection.}, author={Vincenzo Spagnolo and Pietro Patimisco and Riccardo Pennetta and Angelo Sampaolo and Gaetano Scamarcio and Miriam S. Vitiello and Frank K. Tittel}, journal={Optics express}, year={2015}, volume={23 6}, pages={7574-82} }