title: Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy.
abstract: We 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.
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. angelo.sampaolo@uniba.it.|Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. angelo.sampaolo@uniba.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Sampaolo
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. pietro.patimisco@uniba.it.|Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. pietro.patimisco@uniba.it.
authors.forename: Pietro
authors.initials: P
authors.lastname: Patimisco
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. marilena.giglio@uniba.it.
authors.forename: Marilena
authors.initials: M
authors.lastname: Giglio
authors.affiliation: NEST, CNR-Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa I-56127, Italy. miriam.vitiello@sns.it.
authors.forename: Miriam S
authors.initials: MS
authors.lastname: Vitiello
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK. heb1000@cam.ac.uk.
authors.forename: Harvey E
authors.initials: HE
authors.lastname: Beere
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, UK. dar11@cam.ac.uk.
authors.forename: David A
authors.initials: DA
authors.lastname: Ritchie
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. gaetano.scamarcio@uniba.it.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Scamarcio
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA. fkt@rice.edu.
authors.forename: Frank K
authors.initials: FK
authors.lastname: Tittel
authors.affiliation: Dipartimento Interateneo di Fisica, Università degli studi di Bari Aldo Moro e Politecnico di Bari, Via Amendola 173, Bari I-70126, Italy. vincenzoluigi.spagnolo@poliba.it.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Spagnolo
keywords: THz spectroscopy; gas sensing; quantum cascade laser; quartz enhanced photoacoustic spectroscopy; quartz tuning fork