| Oxygen ion is one of the predominant ions in the lower ionosphere. It exists in the courses of chemical reaction and combustion prevalently. However its presence is difficult to detect because of inherent high reactivity and short lifetime. And most courses include transition among excited states with high vibrational levels. Its high-resolution spectrum provides extremely reliable means of unraveling the nature of its structure and monitoring the distribution over quantum states.In this paper, the second negative (A2 u - X2 g) system of O2 was studied in the near infrared region at high resolution using a Ti-Sapphire laser system. The O2+ ion was produced by an ac Penning discharge with high voltage in flowing gases of trace oxygen and large amount of buffering helium. Optical heterodyne magnetic rotation enhanced velocity modulation technique was employed to record rich absorption spectrum. The high vibration levels with v" 18 of the ground electronic state X2 g were obtained under optimized condition. Six hot bands, namely (3, 18), (4, 19), (3, 19), (2, 18), (4, 20) and (6, 20), including over 800 spectra lines were observed and rotationally analyzed for the first time by a non-linear least-square fitting procedure using a standard Hamiltonian, thus, precise molecular constants of the states involved were obtained. The Franck-Condon factors for corresponding transitions were calculated. Because of the relatively large difference (0.291 A) between the equilibrium internuclear separations of the A2 U and X2 g states, the Franck-Condon factors are big for bands with relatively big v. That is to say the corresponding transition probabilities is relativelybig. So it is possible to observe these transitions with high vibrantional states in this paper.
|
PDF Full Text Request