title: Oxygen isotope ratio measurements in CO(2) by means of a continuous-wave quantum cascade laser at 4.3 mum.
abstract: A mid-infrared laser spectrometer was developed for simultaneous high-precision (18)O/(16)O and (17)O/(16)O isotope ratio measurements in carbon dioxide. A continuous-wave, liquid-nitrogen cooled, distributed feedback quantum cascade laser, working at a wavelength of 4.3 microm, was used to probe (12)C(16)O(2), (16)O(12)C(18)O, and (16)O(12)C(17)O lines at ~2311.8 cm(-1). High sensitivity was achieved by means of wavelength modulation spectroscopy with second-harmonic detection. The experimental reproducibility in the short and long terms was deeply investigated through the accurate analysis of a large number of spectra. In particular, we found a short term precision of 0.5 per thousand and 0.6 per thousand, respectively, for (18)O/(16)O and (17)O/(16)O isotope ratios. The occurrence of systematic deviations is also discussed.
authors.affiliation: Dipartimento di Scienze Ambientali, Seconda Università di Napoli, and CNISM-Unità Napoli 2, Via Vivaldi 43, 81100 Caserta, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Castrillo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Casa
authors.forename: Livio
authors.initials: L
authors.lastname: Gianfrani