Rotational analysis of weak (4, 6) hot band in the comet-tail (A2Πi-X2Σ+) system of the CO+

The ro-vibrational spectrum of the weak (4, 6) hot band in the comet-tail (A2Πi-X2Σ+) system of CO+ is observed by employing optical heterodyne and magnetic rotation enhanced velocity modulation spectroscopy. One hundred and twenty-four spectral lines are assigned to this band; thus, precise molecular constants of the levels involved are obtained from a weighted nonlinear least-squares fitting procedure combining with our previous spectrum of the (3, 6) band.

Research highlights► About 1/60 weak band (4, 6) in the comet-tail (A2Πi-X2Σ+) system of CO+ is directly observed. ► 124 spectral lines are assigned to the (4, 6) band. ► Precise molecular constants of the levels involved are obtained. ► The improvement of the molecular constants is up to one order.