{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,14]],"date-time":"2026-05-14T03:06:54Z","timestamp":1778728014463,"version":"3.51.4"},"reference-count":25,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2015,10,14]],"date-time":"2015-10-14T00:00:00Z","timestamp":1444780800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Eric and Wendy Schmidt Transformative Technology Fund"},{"name":"the Walbridge Fund Award from the Princeton Environmental Institute"},{"name":"the Natural Sciences and Engineering Council of Canada"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope (15NO) detection sensitivity of 0.36 ppbv\u00b7Hz\u22121\/2, corresponding to noise-equivalent Faraday rotation angle (NEA) of 1.31 \u00d7 10\u22128 rad\u00b7Hz\u22121\/2 and noise-equivalent absorbance (\u03b1L)min of 6.27 \u00d7 10\u22128 Hz\u22121\/2. White-noise limited performance at 2.8\u00d7 the shot-noise limit is observed up to ~1000 s, allowing reliable calibration and sample measurement within the drift-free interval of the spectrometer. Integration with wet-chemistry based on acidic vanadium(III) enables conversion of aqueous nitrate\/nitrite samples to gaseous NO for total nitrogen isotope analysis. Isotopic ratiometry is accomplished via time-multiplexed measurements of two NO isotope transitions. For 5 \u03bcmol potassium nitrate samples, the instrument consistently yields ratiometric precision below 0.3\u2030, thus demonstrating potential as an in situ diagnostic tool for environmental nitrogen cycle studies.<\/jats:p>","DOI":"10.3390\/s151025992","type":"journal-article","created":{"date-parts":[[2015,10,14]],"date-time":"2015-10-14T10:52:42Z","timestamp":1444819962000},"page":"25992-26008","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer"],"prefix":"10.3390","volume":"15","author":[{"given":"Eric","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stacey","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qixing","family":"Ji","sequence":"additional","affiliation":[{"name":"Department of Geosciences, Princeton University, Princeton, NJ 08544, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael","family":"Silvernagel","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA"},{"name":"Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yin","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA"},{"name":"Now with Healthy Photon, 200 East Guoding Road, Shanghai, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bess","family":"Ward","sequence":"additional","affiliation":[{"name":"Department of Geosciences, Princeton University, Princeton, NJ 08544, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daniel","family":"Sigman","sequence":"additional","affiliation":[{"name":"Department of Geosciences, Princeton University, Princeton, NJ 08544, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gerard","family":"Wysocki","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,10,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"980","DOI":"10.1111\/j.1469-8137.2009.02917.x","article-title":"Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability","volume":"183","author":"Craine","year":"2009","journal-title":"New Phytol."},{"key":"ref_2","first-page":"1","article-title":"Isotopic constraints on glacial\/interglacial changes in the oceanic nitrogen budget","volume":"18","author":"Deutsch","year":"2004","journal-title":"Glob. Geochem. Cycles"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"623","DOI":"10.1029\/1999GB900014","article-title":"Global patterns of terrestrial biological nitrogen (N2) fixation in natural ecosystems","volume":"13","author":"Cleveland","year":"1999","journal-title":"Glob. Geochem. Cycles"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1038\/nature06592","article-title":"An Earth-system perspective of the global nitrogen cycle","volume":"451","author":"Gruber","year":"2008","journal-title":"Nature"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1149","DOI":"10.1029\/1999GB900038","article-title":"The \u03b415N of nitrate in the Southern Ocean: Consumption of nitrate in surface water","volume":"13","author":"Sigman","year":"1999","journal-title":"Glob. Geochem. Cycles"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"304","DOI":"10.3402\/tellusb.v42i3.15223","article-title":"15N\/14N ratios of NOx from vehicle engines and coal-fired power stations","volume":"42","author":"Heaton","year":"1990","journal-title":"Tellus"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"124","DOI":"10.2134\/jeq2004.1240","article-title":"Assessment of a \u03b415N isotopic method to indicate anthropogenic eutrophication in aquatic ecosystems","volume":"33","author":"Cole","year":"2004","journal-title":"J. Environ. Qual."},{"key":"ref_8","first-page":"737","article-title":"Human alteration of the global nitrogen cycle: Sources and consequences","volume":"7","author":"Vitousek","year":"1997","journal-title":"Ecol. Appl."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/S0269-7491(98)80010-9","article-title":"The global nitrogen cycle: Changes and consequences","volume":"102","author":"Galloway","year":"1998","journal-title":"Environ. Pollut."},{"key":"ref_10","first-page":"503","article-title":"Nitric oxide as a unique signaling molecule in the vascular system: A historical overview","volume":"53","author":"Ignarro","year":"2002","journal-title":"J. Physiol. Pharmacol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"11460","DOI":"10.1073\/pnas.93.21.11460","article-title":"Whole body nitric oxide synthesis in healthy men determined from [15N]arginine-to-[15N] citrulline labelling","volume":"93","author":"Castillo","year":"1996","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"7764","DOI":"10.1073\/pnas.78.12.7764","article-title":"Nitrate biosynthesis in man","volume":"78","author":"Green","year":"1981","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Wang, Y., Nikodem, M., Zhang, E., Cikach, F., Barnes, J., Comhair, S., Dweik, R.A., Kao, C., and Wysocki, G. (2015). Shot-noise limited Faraday rotation spectroscopy for detection of nitric oxide isotopes in breath, urine, and blood. Sci. Rep., 5.","DOI":"10.1038\/srep09096"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1783","DOI":"10.1364\/OL.39.001783","article-title":"Dual modulation Faraday rotation spectroscopy of HO2 in a flow reactor","volume":"39","author":"Brumfield","year":"2014","journal-title":"Opt. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Zhang, E.J., Huang, S., Silvernagel, M., and Wysocki, G. (2015, January 10\u201315). Transportable dual modulation Faraday rotation spectrometer time-multiplexed nitric oxide isotope ratiometry. Proceedings of the Conference on Lasers and Electro-Optics, San Jose, CA, USA.","DOI":"10.1364\/CLEO_AT.2015.ATu4J.2"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2715","DOI":"10.1021\/ac00199a007","article-title":"Nanogram nitrite and nitrate determination in environmental and biological materials by vanadium(III) reduction with chemiluminescence detection","volume":"61","author":"Braman","year":"1989","journal-title":"Anal. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"29727","DOI":"10.1364\/OE.20.029727","article-title":"Faraday rotation spectroscopy based on permanent magnets for sensitive detection of oxygen at atmospheric conditions","volume":"28","author":"Brumfield","year":"2012","journal-title":"Opt. Exp."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1007\/s00340-010-4002-1","article-title":"VCSEL based Faraday rotation spectroscopy with a modulated and static magnetic field for trace molecular oxygen detection","volume":"102","author":"So","year":"2011","journal-title":"Appl. Phys. B"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"12587","DOI":"10.1073\/pnas.0906291106","article-title":"Ultrasensitive detection of nitric oxide at 5.33 \u00b5m by using external cavity quantum cascade laser-based Faraday rotation spectroscopy","volume":"106","author":"Lewicki","year":"2009","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_20","first-page":"15958","article-title":"Hybrid-Faraday rotation spectrometer for sub-ppm detection of atmospheric O2","volume":"22","author":"Zhang","year":"2014","journal-title":"Opt. Exp."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1007\/BF00697632","article-title":"A differential detection scheme for Faraday rotation spectroscopy with a color center laser","volume":"34","author":"Adams","year":"1984","journal-title":"Appl. Phys. B"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1007\/BF00663152","article-title":"Highly sensitive polarimetric techniques","volume":"37","author":"Zapasskii","year":"1982","journal-title":"J. Appl. Spect."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3276","DOI":"10.1063\/1.1729177","article-title":"Modulation broadening of NMR and ESR lineshapes","volume":"34","author":"Wilson","year":"1963","journal-title":"J. Appl. Phys."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Hodgkinson, J., and Tatam, R.P. (2013). Optical gas sensing: A review. Meas. Sci. Technol., 24.","DOI":"10.1088\/0957-0233\/24\/1\/012004"},{"key":"ref_25","unstructured":"Sigman, D.M., Karsh, K.L., and Casciotti, K.L. (2009). Encyclopedia of Ocean Science, Elsevier."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/10\/25992\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T20:50:03Z","timestamp":1760215803000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/15\/10\/25992"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2015,10,14]]},"references-count":25,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2015,10]]}},"alternative-id":["s151025992"],"URL":"https:\/\/doi.org\/10.3390\/s151025992","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2015,10,14]]}}}