Applications of cavity ring-down spectroscopy to high precision isotope ratio measurement of 13C/12C in carbon dioxide.
Recent measurements of carbon isotopes in carbon dioxide using near-infrared, diode-laser-based cavity ring-down spectroscopy (CRDS) are presented. The CRDS system achieved good precision, often better than 0.2 per thousand, for 4% CO2 concentrations, and also achieved 0.15-0.25 per thousand precision in a 78 min measurement time with cryotrap-based pre-concentration of ambient CO2 concentrations (360 ppmv). These results were obtained with a CRDS system possessing a data rate of 40 ring-downs per second and a loss measurement of 4.0 x 10(-11) cm(-1) Hz(-1/2). Subsequently, the measurement time has been reduced to under 10 min. This standard of performance would enable a variety of high concentration (3-10%) isotopic measurements, such as medical human breath analysis or animal breath experiments. The extension of this ring-down to the 2 microm region would enable isotopic analysis at ambient concentrations, which, combined with the small size, robust design, and potential for frequent measurements at a remote site, make CRDS technology attractive for remote atmospheric measurement applications.
Wahl
Ed H
EH
Picarro Inc., Sunnyvale, CA 94085, USA.
Fidric
Bernard
B
Rella
Chris W
CW
Koulikov
Sergei
S
Kharlamov
Boris
B
Tan
Sze
S
Kachanov
Alexander A
AA
Richman
Bruce A
BA
Crosson
Eric R
ER
Paldus
Barbara A
BA
Kalaskar
Shashi
S
Bowling
David R
DR
D000388:Air / Q000032:analysis*; D002245:Carbon Dioxide / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry*; D006801:Humans; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation / Q000379:methods
D002247:Carbon Isotopes; D002245:Carbon Dioxide