Rotational analysis of the (3, 6) band in the comet-tail (A2Πi -X2Σ+) system of CO+

The direct observation and rotational analysis of the (3, 6) band in the comet-tail (A2Πi-X2Σ+) system of CO+ are carried out for the first time employing optical heterodyne and magnetic rotation enhanced velocity modulation spectroscopy. That 193 lines are assigned to this band ranging from 12 100 to 12 370 cm−1 results in most accurate molecular constants by nonlinear least-squares fitting procedure employing the effective Hamiltonians.