Study On The Ro-vibrational Spectrum Of The A～2Π-X～2Σ～+ System Of N₂～+ And CO～+

Molecular ions are abundant in the interstellar space, chemical reaction,combustion and electric discharge plasma. The spectra of the molecular ions are themost important foundation of the relevant studies and applications. However, due tothe shorter lifetime, stronger chemical reaction and lower laboratory reachableconcentration of the molecular ions, their spectra are hard to obtain. Moreover, theirspectra are often disturbed by those much more intense ones of their neutral precursormolecules.Optical heterodyne detected velocity modulation spectroscopy (OH-VMS) andoptical heterodyne and magnetic rotation enhanced velocity modulation spectroscopy(OH-MR-VMS) are employed to obtain the absorption spectra of the A²âˆ-X²âˆ‘⁺transition of N₂⁺ and CO⁺ respectively. Three hundred and ten lines are assigned to the(2, 0) band of the Meinel system ((A²âˆ_u-X²âˆ‘_g⁺) of N₂⁺ in the range of 12400-12800cm^-1. And 655 lines, namely, 244 to the (0, 3), 218 to the (1, 4) and 193 to the (3, 6)band, are also assigned to the comet-mail system (A²âˆ_i-X²âˆ‘⁺) of CO⁺. Furthermore,the direct observation and ro-vibronic analysis of the (1, 4) and (3, 6) bands arecarried out for the first time. The most accurate molecular constants of the levelsinvolved are obtained by weighted nonlinear least-squares fitting the effectiveHamiltonians, and most of the constants are improved over twice.Additionally, the RKR potentials and the vibration energy levers involved in thecomet-tail system of CO⁺ are calculated employing the equilibrium molecularconstants, and thus plotted. The perturbations of v'=0, 5, 10 vibrational states of theA²âˆ_i state with v"=10, 14, 18 of the X²âˆ‘⁺ state, respectively, are clearly shown. TheFranck-Condon factors are calculated and listed as well.