CENTRAL TUNING DIP IN A SUBMILLIMETER MOLECULAR LASER

Abstract

A central tuning dip (or ``Lamb dip'') has been observed in the power output of a CW molecular laser operating at 118.6 μ. The collision broadened linewidth was calculated from the shape of the dip. From the dependence of the linewidth on pressure, a radiative lifetime of 0.64 μsec and a pressure broadening (full width) of 10 MHz/torr H2O can be estimated. Comparisons with published results for OH and H2O do not yield sufficient information to identify either as the lasing species.