{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T00:00:14Z","timestamp":1768348814059,"version":"3.49.0"},"reference-count":21,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2009,4,16]],"date-time":"2009-04-16T00:00:00Z","timestamp":1239840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We report on the development of a photoacoustic sensor for the detection of formaldehyde (CH2O) using a thermoelectrically cooled distributed-feedback quantum cascade laser operating in pulsed mode at 5.6 mm. A resonant photoacoustic cell, equipped with four electret microphones, is excited in its first longitudinal mode at 1,380 Hz. The absorption line at 1,778.9 cm-1 is selected for CH2O detection. A detection limit of 150 parts per billion in volume in nitrogen is achieved using a 10 seconds time constant and 4 mW laser power. Measurements in ambient air will require water vapour filters.<\/jats:p>","DOI":"10.3390\/s90402697","type":"journal-article","created":{"date-parts":[[2009,4,16]],"date-time":"2009-04-16T08:37:34Z","timestamp":1239871054000},"page":"2697-2705","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":34,"title":["Quantum Cascade Laser-Based Photoacoustic Sensor for Trace Detection of Formaldehyde Gas"],"prefix":"10.3390","volume":"9","author":[{"given":"Angela","family":"Elia","sequence":"first","affiliation":[{"name":"Dipartimento Interateneo di Fisica \u201cM. Merlin\u201d, Universit\u00e0 and Politecnico of Bari, and Laboratorio Regionale CNR-INFM \u201cLIT3\u201d, Bari, I-70126, Italy"}]},{"given":"Cinzia","family":"Di Franco","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica \u201cM. Merlin\u201d, Universit\u00e0 and Politecnico of Bari, and Laboratorio Regionale CNR-INFM \u201cLIT3\u201d, Bari, I-70126, Italy"}]},{"given":"Vincenzo","family":"Spagnolo","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica \u201cM. Merlin\u201d, Universit\u00e0 and Politecnico of Bari, and Laboratorio Regionale CNR-INFM \u201cLIT3\u201d, Bari, I-70126, Italy"}]},{"given":"Pietro Mario","family":"Lugar\u00e0","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica \u201cM. Merlin\u201d, Universit\u00e0 and Politecnico of Bari, and Laboratorio Regionale CNR-INFM \u201cLIT3\u201d, Bari, I-70126, Italy"}]},{"given":"Gaetano","family":"Scamarcio","sequence":"additional","affiliation":[{"name":"Dipartimento Interateneo di Fisica \u201cM. Merlin\u201d, Universit\u00e0 and Politecnico of Bari, and Laboratorio Regionale CNR-INFM \u201cLIT3\u201d, Bari, I-70126, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2009,4,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2413","DOI":"10.1016\/0004-6981(84)90011-8","article-title":"Importance of formaldehyde in cloud chemistry","volume":"18","author":"Adewuyi","year":"1984","journal-title":"Atmos. Environ"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1007\/BF00321533","article-title":"Determination of volatile carbonyl compounds in clean air","volume":"340","author":"Slemr","year":"1991","journal-title":"Fresenius J. Anal. 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D"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3461","DOI":"10.1029\/2000GL011857","article-title":"Satellite observations of formaldehyde over North America from GOME","volume":"27","author":"Chance","year":"2000","journal-title":"Geophys. Res. Lett"},{"key":"ref_7","unstructured":"Available online: http:\/\/www.osha.gov \/ SLTC\/ formaldehyde \/, accessed January 2009."},{"key":"ref_8","unstructured":"Available online: http:\/\/www.epa.gov\/lawsregs\/, accessed January 2009."},{"key":"ref_9","unstructured":"Available online: http:\/www.epa.gov\/osw\/hazard\/testmethods\/sw846, accessed January 2009."},{"key":"ref_10","unstructured":"Eller, P.M., and Cassinelli, M.E. (1994). NIOSH Manual of Analytical methods, U.S. Department of Health and Human Services. [4th Ed]. 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JQSRT, in press.","DOI":"10.1016\/j.jqsrt.2008.11.005"},{"key":"ref_19","unstructured":"Available online: http:\/\/www.hitran.com, accessed January 2009."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"799","DOI":"10.1007\/s00340-004-1659-3","article-title":"Formaldehyde sensor using interband cascade laser based quartz-enhanced photoacoustic spectroscopy","volume":"79","author":"Horstjann","year":"2004","journal-title":"Appl. Phys. B"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1007\/s00340-006-2295-x","article-title":"Photoacoustic spectroscopy of formaldehyde with tunable laser radiation at the parts per billion level","volume":"85","author":"Angelmahar","year":"2006","journal-title":"Appl. Phys. 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