{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,12]],"date-time":"2026-02-12T09:44:40Z","timestamp":1770889480830,"version":"3.50.1"},"reference-count":45,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2020,8,21]],"date-time":"2020-08-21T00:00:00Z","timestamp":1597968000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100012774","name":"Innovationsfonden","doi-asserted-by":"publisher","award":["158-00003B"],"award-info":[{"award-number":["158-00003B"]}],"id":[{"id":"10.13039\/100012774","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Quartz-enhanced photoacoustic sensing is a promising method for low-concentration trace-gas monitoring due to the resonant signal enhancement provided by a high-Q quartz tuning fork. However, quartz-enhanced photoacoustic spectroscopy (QEPAS) is associated with a relatively slow acoustic decay, which results in a reduced spectral resolution and signal-to-noise ratio as the wavelength tuning rate is increased. In this work, we investigate the influence of wavelength scan rate on the spectral resolution and signal-to-noise ratio of QEPAS sensors. We demonstrate the acquisition of photoacoustic spectra from 3.1 \u03bcm to 3.6 \u03bcm using a tunable mid-infrared optical parametric oscillator. The spectra are attained using wavelength scan rates differing by more than two orders of magnitude (from 0.3 nm s\u22121 to 96 nm s\u22121). With this variation in scan rate, the spectral resolution is found to change from 2.5 cm\u22121 to 9 cm\u22121. The investigated gas samples are methane (in nitrogen) and a gas mixture consisting of methane, water, and ethanol. For the gas mixture, the reduced spectral resolution at fast scan rates significantly complicates the quantification of constituent gas concentrations.<\/jats:p>","DOI":"10.3390\/s20174725","type":"journal-article","created":{"date-parts":[[2020,8,21]],"date-time":"2020-08-21T09:21:51Z","timestamp":1598001711000},"page":"4725","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Intrinsic Spectral Resolution Limitations of QEPAS Sensors for Fast and Broad Wavelength Tuning"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2689-1169","authenticated-orcid":false,"given":"Jesper B.","family":"Christensen","sequence":"first","affiliation":[{"name":"Danish Fundamental Metrology, Kogle All\u00e9 5, 2970 H\u00f8rsholm, Denmark"}]},{"given":"Lasse","family":"H\u00f8gstedt","sequence":"additional","affiliation":[{"name":"NLIR Aps, Hirsemarken 1, 3520 Farum, Denmark"}]},{"given":"S\u00f8ren M. M.","family":"Friis","sequence":"additional","affiliation":[{"name":"NLIR Aps, Hirsemarken 1, 3520 Farum, Denmark"}]},{"given":"Jui-Yu","family":"Lai","sequence":"additional","affiliation":[{"name":"HC Photonics, 4F, No. 2, Technology Rd. V, Hsinchu City 300, Taiwan"}]},{"given":"Ming-Hsien","family":"Chou","sequence":"additional","affiliation":[{"name":"HC Photonics, 4F, No. 2, Technology Rd. V, Hsinchu City 300, Taiwan"}]},{"given":"David","family":"Balslev-Harder","sequence":"additional","affiliation":[{"name":"Danish Fundamental Metrology, Kogle All\u00e9 5, 2970 H\u00f8rsholm, Denmark"}]},{"given":"Jan C.","family":"Petersen","sequence":"additional","affiliation":[{"name":"Danish Fundamental Metrology, Kogle All\u00e9 5, 2970 H\u00f8rsholm, Denmark"}]},{"given":"Mikael","family":"Lassen","sequence":"additional","affiliation":[{"name":"Danish Fundamental Metrology, Kogle All\u00e9 5, 2970 H\u00f8rsholm, Denmark"}]}],"member":"1968","published-online":{"date-parts":[[2020,8,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"012004","DOI":"10.1088\/0957-0233\/24\/1\/012004","article-title":"Optical gas sensing: A review","volume":"24","author":"Hodgkinson","year":"2013","journal-title":"Meas. Sci. 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