Knowledge Bank

The absorption spectrum of metastable $a3\Pi$ CO has been measured in the infrared using a diode laser. The molecule was generated in an air cooled a.c. discharge and signals were detected using concentration modulation (2f detection). Most of the lines can be assigned to the fundamental band ($\Omega =0,1,2$) based on predictions from optical $spectroscopy.1$ Lambda doubling splittings in the $\Omega =1$ and 2 manifolds are in good agreement with molecular beam $r.f.2$ and $microwave5$ results when available. The much larger $\Omega =0$ lambda doublings are easily resolved in the diode laser spectra and provide information on the doubling in this sub-state of the molecule which is not available from * or microwave results.