FAR-INFRARED LASER MAGNETIC RESONANCE SPECTRA OF $a^{3}\Pi$ CO

Author Institution:Pure rotational transitions have been observed in the metastable $a^{3}\Pi$ State of carbon monoxide, generated in a glow discharge through a CO-He mixture at near-ambient temperature. Well-resolved spectra at 393.6 $\mu m (HCOOH)$ and 458.5 $\mu m (HCOOH)$ ore assigned to the $J=6 \rightarrow 7$ and $J = 5 \rightarrow 6$ transitions in the $\Omega=2$ state, respectively. A more overlapped spectrum observed at 601.9 $\mu m (CH_{2}CHCI)$ is tenatively attributed to the $J = 4 \rightarrow 5$ transition in $\Omega =1$. Another weak series of lines found at 699 $\mu m (CH_{3}OH)$ appears to be the $N = 7 \rightarrow 8$ transition in the more short-lived $a^{\prime}\ ^{3}\Sigma^{+}$ state of CO. These results are being analyzed along with earlier data In hopes of obtaining an uncorrelated, physically meaningful set of molecular parameters for the $a^{3}\Pi$ state