title: Measuring the 13C/12C isotope ratio in atmospheric CO2 by means of laser absorption spectrometry: a new perspective based on a 2.05-microm diode laser.
abstract: The potential use of high sensitivity laser absorption spectroscopy for measuring the 13C/12C isotope ratio in atmospheric CO2 has been demonstrated, using a GaSb-based diode laser at 2.05 microm. In this spectral region, the overlapping between relatively strong 12CO2 and 13CO2 absorption features gives rise to several line pairs which are well suitable for a spectroscopic determination of the isotope ratio. Preliminary results have demonstrated that a short-term precision better than 1 per thousand can be easily obtained, for a CO2 concentration of 1000 ppm. We extensively discuss the influence of a possible non-linearity in the detectors' response on the delta-value and suggest an instrumental development that would allow to eliminate this effect.
authors.affiliation: Dipartimento di Scienze Ambientali, Seconda Università di Napoli, CNISM, 81100 Caserta, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Castrillo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Casa
authors.forename: Antonio
authors.initials: A
authors.lastname: Palmieri
authors.forename: Livio
authors.initials: L
authors.lastname: Gianfrani
mesh_terms: D000388:Air / Q000032:analysis*; D002245:Carbon Dioxide / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry*; D006801:Humans; D007834:Lasers; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation / Q000379:methods
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide