Rotational analysis of (6, 20), (4, 20), and (2, 18) bands in the second negative (A2Πu-X2Πg) system of 16O2+ cation

The second negative (A2Πu-X2Πg) system of O2+ were investigated in the 12100-14100 cm−1 near infrared region at high resolution by employing optical heterodyne magnetic rotation enhanced velocity modulation technique. Three new hot bands (2, 18), (4, 40) and (6, 20) were observed for the first time. From the rotational analysis of the line positions, precise molecular constants of the states involved were determined with an accuracy of 0.0028 cm−1.