Spagnolo, VincenzoPatimisco, PietroPennetta, RiccardoSampaolo, AngeloScamarcio, GaetanoVitiello, Miriam S.Tittel, Frank K.2016-06-222016-06-222015Spagnolo, Vincenzo, Patimisco, Pietro, Pennetta, Riccardo, et al.. "THz Quartz-enhanced photoacoustic sensor for H2S trace gas detection." <i>Optics Express,</i> 23, no. 6 (2015) The Optical Society: 7574-7582. http://dx.doi.org/10.1364/OE.23.007574.https://hdl.handle.net/1911/90525We 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 αmin = 2.3·10−7 cm−1 and a normalized noise-equivalent absorption NNEA = 4.4·10−10W·cm−1·Hz-1/2, several times lower than the values previously reported for near-IR and mid-IR H2S QEPAS sensors.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttp://dx.doi.org/10.1364/OE.23.007574