Sampaolo, AngeloPatimisco, PietroGiglio, MarilenaVitiello, Miriam S.Beere, Harvey E.Ritchie, David A.Scamarcio, GaetanoTittel, Frank K.Spagnolo, Vincenzo2016-06-272016-06-272016Sampaolo, Angelo, Patimisco, Pietro, Giglio, Marilena, et al.. "Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy." <i>Sensors,</i> 16, no. 4 (2016) MDPI AG: http://dx.doi.org/10.3390/s16040439.https://hdl.handle.net/1911/90582We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH₃OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a 3.93 THz quantum cascade laser as the excitation source in resonance with a CH₃OH rotational absorption line located at 131.054 cm(-1). A minimum detection limit of 160 ppb in 30 s integration time, corresponding to a normalized noise equivalent absorption NNEA = 3.75 × 10(-11) cm(-1)W/Hz(½), was achieved, representing a nearly one-order-of-magnitude improvement with respect to previous reports.engThis article is an open access article distributed under the terms and conditions of the Creative Commons by Attribution (CC-BY) license.Journal articlequartz enhanced photoacoustic spectroscopyquartz tuning forkgas sensingTHz spectroscopyquantum cascade laserhttp://dx.doi.org/10.3390/s16040439