{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,25]],"date-time":"2025-10-25T12:05:34Z","timestamp":1761393934211,"version":"build-2065373602"},"reference-count":28,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2010,7,9]],"date-time":"2010-07-09T00:00:00Z","timestamp":1278633600000},"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 have developed an efficient and compact 3.4 \u03bcm difference-frequency-generation spectrometer using a 1.55 \u03bcm distributed feedback (DFB) laser diode, a 1.06 \u03bcm DFB laser diode, and a ridge-waveguide periodically poled lithium niobate. It is continuously tunable in the 30 cm\u20131 span and is applied to 12CH3D\/12CH4 isotope ratio measurements. The suitable pair of 12CH3D n4 pP(7,6) and 12CH4 \u03bd2+\u03bd4 R(6) F1(1) lines enabled us to determine their isotope ratio with a precision repeatability of 0.8\u2030 using a sample and a working standard of pure methane with an effective signal averaging time of 100 ms.<\/jats:p>","DOI":"10.3390\/s100706612","type":"journal-article","created":{"date-parts":[[2010,7,9]],"date-time":"2010-07-09T11:39:55Z","timestamp":1278675595000},"page":"6612-6622","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["An Efficient and Compact Difference-Frequency-Generation Spectrometer and Its Application to 12CH3D\/12CH4 Isotope Ratio Measurements"],"prefix":"10.3390","volume":"10","author":[{"given":"Kiyoshi","family":"Tsuji","sequence":"first","affiliation":[{"name":"Department of Environmental Science and Technology, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology\/4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8502, Japan"},{"name":"SENTAN, Japan Science and Technology Agency\/Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan"}]},{"given":"Hiroaki","family":"Teshima","sequence":"additional","affiliation":[{"name":"SENTAN, Japan Science and Technology Agency\/Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan"},{"name":"Department of Physics, Faculty of Science and Technology, Keio University\/3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan"}]},{"given":"Hiroyuki","family":"Sasada","sequence":"additional","affiliation":[{"name":"SENTAN, Japan Science and Technology Agency\/Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan"},{"name":"Department of Physics, Faculty of Science and Technology, Keio University\/3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan"}]},{"given":"Naohiro","family":"Yoshida","sequence":"additional","affiliation":[{"name":"Department of Environmental Science and Technology, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology\/4259, Nagatsuta-cho, Midori-ku, Yokohama, 226-8502, Japan"},{"name":"SENTAN, Japan Science and Technology Agency\/Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan"}]}],"member":"1968","published-online":{"date-parts":[[2010,7,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1007\/s00340-007-2576-z","article-title":"Mid-infrared spectroscopic determination of isotope ratios of N2O at trace levels using wavelength modulation and balanced path length detection","volume":"87","author":"Waechter","year":"2007","journal-title":"Appl. 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[1st ed]."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/10\/7\/6612\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T22:02:53Z","timestamp":1760220173000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/10\/7\/6612"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2010,7,9]]},"references-count":28,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2010,7]]}},"alternative-id":["s100706612"],"URL":"https:\/\/doi.org\/10.3390\/s100706612","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2010,7,9]]}}}