Measurement of Molecular Spectroscopy and Kinetics in Gas Phase by Means of CRDS Technique

Recent years a new technique,Cavity-Ring-Down spectroscopy (CRDS),has been developed quickly,which allows an increase of several orders of magnitude in sensitivity over existing techniques for the wide spectral region accessible with tunable pulsed lasers.The principle of operation is based,not on the measurement of the absorbed signal strength for a given sample path,but of the time rate of decay of a pulse of light trapped in a high reflectance opticalc avity.Due to its many advantages,it has become a powerful tool for spectroscopic measurement of weak transitions.This sensitive technique was extended for kinetic measurement for the first time by M.C.Lin et al..They used this new technique successfully to measure the absolute values of rate constants for several C₆H₅ reactions.The application of CRDS technique to molecular spectroscopy and kinetics in gas phase is described briefly.A portion of the I₂(B³∏(0_u⁺)←X¹∑_g⁺) continuous spectrum has been recorded by means of CRDS technique for the first time.The reflectivity of the mirrors has been measured by means of CRDS technique.The vapor pressure of I₂ was 0.1Pa and pulsed dye laser energy was 0.1mJ.