title: Site-selective nitrogen isotopic ratio measurement of nitrous oxide using 2 microm diode lasers.
abstract: We demonstrate a high-precision measurement of the isotopomer abundance ratio 14N(15)N(16)O/15N(14)N(16)O/14N(14)N(16)O (approximately 0.37/0.37/100) using three wavelength-modulated 2 microm diode lasers combined with a multipass cell which provides different optical pathlengths of 100 and 1 m to compensate the large abundance difference. A set of absorption lines for which the absorbances have almost the same temperature dependence are selected so that the effect of a change in gas temperature is minimized. The test experiment using pure nearly natural-abundance N(2)O samples showed that the site-selective 15N/14N ratios can be measured relative to a reference material with a precision of +/-3 x 10(-4) (+/-0.3 per thousand) in approximately 2 h.
authors.affiliation: Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Uehara
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Kikugawa
authors.forename: N
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D007834:Lasers; D009587:Nitrogen Isotopes / Q000737:chemistry; D009609:Nitrous Oxide / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D009587:Nitrogen Isotopes; D009609:Nitrous Oxide