Knowledge Bank

Saturation Stark spectroscopy of Carbonyl Sulfide has been pursued with our Stark cell inside a $CO2$ laser cavity. The measurements have been extended to weak hot bands and to high J transitions with quite small Stark shifts. One of them is the R(64) line of the $\Delta -\Sigma$ transition $O22OC\leftarrow 0000$, a forbidden transition slightly allowed through the l-type resonance between $0220$ and $0200$. This measurement confirms our assignment of the CW laser emission in OCS observed by B.M. Landsberg [1]: the $9R8CO2$ laser beam is pumping from ($0000J=64$) to $(0220,J=65)$ and the laser emission reaches the $(0220c,J=64)$ level. A microwave coupler has been adapted to our Stark cell to perform, for the first time, Intracavity Laser Microwave Double Resonance experiments under electrical fields up to 100 kV/cm. Many DR lines are observed in the 10 to 50 GHz range, both in upper and lower vibrational states of OCS Stark transitions. The intracavity sensitivity yields high signal to noise ratios. The width (1 to 2 MHz) of the perfectly symmetrical lines allows frequency measurements within 100 kHz. Those new data have been added to our previous Stark results and combined with a few MBER measurements from F.H. de Leeuw [2] to improve the determination of the electrical properties of OCS.