Knowledge Bank

Laser Induced Fluorescence (LIF) and Stimulated Emission Pumping (SEP) are used to characterize the $CD2$ $a¯1A1⟷b¯\prime B1$ rovibronic transitions. $CD2$ is generated from photolysis of $d2$-ketene. Rotational constants and vibrational term values of both electronic states have been determined. Perturbations to the ^{a} state rotation-vibration level energies caused by singlet-triplet coupling appeared to be more prominent in $CD2$ than in $CH2$. The ratio of the $\Delta Ka=3/\Delta Ka=1$ transition intensities is compared with the ones of the $CH2$ transitions. This allows us to assess the importance of the Renner-Teller effect in inducing the abnormally strong $\Delta Ka=3$ transitions.