Knowledge Bank

A polarization detection method was demonstrated for Stimulated Emission Spectroscopy (SES) in the study of the vibration-rotation levels of X, Ag glyoxal. The polarization methods allowed detection of a stimulated emission signal as small as $10-1$ of the stimulating laser intensity, while the laser pulses had 10% fluctuation in intensity. Analysis of the intensity and the polarization of the stimulating photons unambiguously showed that the observed spectral lines resulted from a stimulated emission process. The vibrational term value of the $v2=2CO$ stretch level was measured to be $3473.2=0.2cm-1$ and the vibrational constants for the $\nu 2$ mode were determined as $\omega =1745.8(5)cm-1$ and $X22=-4.6(5)cm-1$. It was observed that the $K2+$) rotational levels are perturbed by an a-axis Coriolis coupling. Only the B and C rotational constants are accurately determined as 0.1584(8) and $0.1500(10)cm-1$.