N+2(A→X) and N+2(B→X) fluorescence excitation spectra by photon impact

Abstract

N⁺₂(A ²Π_u→X ²Σ⁺_g) and N⁺₂(B ²Σ⁺_u→X ²Σ⁺_g) fluorescence excitation spectra were measured using synchrotron radiation from threshold to 38 eV. Rydberg series converging to N⁺₂ B ²Σ⁺_u is seen to autoionize, with a 85% branching ratio into the A ²Π_u continuum. For series converging to B ²Σ⁺_u(v = 1), vibrational autoionization observed into the B(v = 0) continuum, is shown to compete efficiently with electronic autoionization. Above 20 eV, Rydberg series converging to N⁺₂, C ²Σ⁺_u as well as a number of unidentified resonances are shown to be coupled to each or both the A and B ionization continua.