Abstract

For high sensitivity measurements of isotope concentration - ratios of trace-level gas mixtures, particularly including carbon dioxide isotopes, we tested a ¹² CO₂ - ¹³ CO₂ composite laser system containing intracavity absorption-ells. Sensitivity enhancement obtainable by the intracavity modulation absorption-cell with synchronous detection scheme was examined theoretically. ¹³CO₂ in atmospheric air was readily detected and minimum detectable concentration by the present system was estimated to be 70 ppb.

© 2001 IEEE