INFRARED CAVITY RINGDOWN LASER-ABSORPTION SPECTROSCOPY (IR-CRLAS)

We report the first extension of cavity ringdown laser absorption spec troscopy (CRLAS) into the infrared region. Spectra of static gas sampl es have been obtained employing a single mode Nd:YAG pumped optical pa rametric oscillator laser system and ate reported for two spectral reg ions centered around 1.6 and 3.3 mu m, respectively. We also explore t he issue of the frequency specificity of the ringdown cavity. Specific ally, we demonstrate the ability to extract accurate absorption intens ities when the width of the spectral feature is much smaller than the free spectral range of the cavity, in direct contrast to recently publ ished theoretical predictions.