Trace moisture measurement in HCl gas by near-infrared diode LASER spectroscopy

We have developed a laser absorption spectroscopy with a near-infrared distributed-feedback (DFB) laser diode as an in-situ and real time monitoring system in relation to future ultra-large scale integration (ULSI) technology. There we have found the existence of the H/sub 2/O-HCl cluster formed by hydrogen association in HCl gas. We have also demonstrated that the moisture in HCl gas can be precisely estimated by measurement of a vibrational spectrum of the isolated H/sub 2/O molecule itself while dissociating the cluster by probing laser energy.