Wahl Ed H, Fidric Bernard, Rella Chris W, Koulikov Sergei, Kharlamov Boris, Tan Sze, Kachanov Alexander A, Richman Bruce A, Crosson Eric R, Paldus Barbara A, Kalaskar Shashi, Bowling David R
Picarro Inc., Sunnyvale, CA 94085, USA.
Isotopes Environ Health Stud. 2006 Mar;42(1):21-35. doi: 10.1080/10256010500502934.
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.
介绍了近期使用基于近红外二极管激光器的光腔衰荡光谱技术（CRDS）对二氧化碳中的碳同位素进行的测量。对于4%的二氧化碳浓度，该CRDS系统实现了良好的精度，通常优于千分之0.2；在基于低温阱预浓缩环境二氧化碳浓度（360 ppmv）的78分钟测量时间内，精度也达到了千分之0.15 - 0.25。这些结果是通过一个数据采集速率为每秒40次衰荡、损耗测量为4.0×10⁻¹¹ cm⁻¹ Hz⁻¹/²的CRDS系统获得的。随后，测量时间已缩短至10分钟以内。这种性能标准将能够进行各种高浓度（3 - 10%）的同位素测量，例如医学上的人体呼吸分析或动物呼吸实验。将这种衰荡技术扩展到2微米区域将能够在环境浓度下进行同位素分析，再结合其小尺寸、坚固的设计以及在偏远地点频繁测量的潜力，使得CRDS技术在远程大气测量应用中颇具吸引力。
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