Electron impact excitation of a higher lying metastable state of carbon monoxide

A higher lying '10 eV' metastable state of CO has been isolated for the first time from the influence of the a 3 Pi state. Accurate evaluations of the observed lifetime have been made for a wide range of incident energies and established as 80+or-10 mu s. The total excitation cross section of the state has been measured under high electron resolution and the threshold accurately determined as lying at 9.45 eV with a possible second threshold at 10.45 eV. The I 1 Sigma - is affirmed as the most likely candidate for this higher lying metastable state.