Rapid-Swept CW Cavity Ring-down Laser Spectroscopy for Carbon Isotope Analysis

Abstract

With the aim of developing a portable system for an in field isotope analysis, we investigate an isotope analysis based on rapid-swept CW cavity ring-down laser spectroscopy, in which the concentration of a chemical species is derived from its photo absorbance. Such a system can identify the isotopomer and still be constructed as a quite compact system. We have made some basic experimental measurements of the overtone absorption lines of carbon dioxide ( 12 C 16 O 2 , 13 C 16 O 2 ) by rapid-swept cavity ring-down spectroscopy with a CW infrared diode laser at 6,200 cm À1 (1.6 mm). The isotopic ratio has been obtained as ð1:07AE0:13ÞÂ10 À2 , in good agreement with the natural abundance within experimental uncertainty. The detection sensitivity in absorbance has been estimated to be 3Â10 À8 cm À1 .