Detecting different gases in their specific excited electronic states is an ongoing challenge for plasma physics. Cavity Ring-Down Spectroscopy (CRDS) due to its high sensitivity compared to multipass absorption schemes can be used to analyse population of electronic states of different molecules that are present only in trace amounts in a discharge.
Several previously unreported transitions of the a' 3 Σ+ - a3 Πr (1-1) system of carbon monoxide were detected in a He/H2/CO gas mixture in the wavenumber range 6390-6400 cm-1.