Investigation of N2+ (C2Σu+ → X2Σg+ fluorescence excited through auger decay of the 1s−1π* resonance

A theoretical investigation of N2+ (C2Σu+ → X2Σg+ molecular fluorescence excited through the Auger decay of the 1s−1π* resonance is carried out. The fluorescence cross sections are calculated with due regard for the dependence of the matrix element of the C → X dipole transition on the internuclear distance, the interference between channels of excitation via different vibrational levels vr of the 1s−1π* resonance, the rotational structure of the fluorescence band, and the predissociation of the N2+C2Σu+v′ ≥3) states. The calculated cross sections are in good agreement with the experimental results of recent measurements. The results of the calculations have demonstrated that the observed dependence of the cross section of the (C2Σu+ (v′) → X2Σg+ (v″) fluorescence on the excitation energy and the fluorescence wavelength for a group of bands with equal values of the difference Δv = v′ − v″ is associated with transitions between the vibrational levels of the electronic states involved in the excitation and subsequent cascade decay of the 1s−1π* resonance: N2 (v0 = 0) → N*2(1s−1π*(vr)) ⇒ N2+: (C2Σu+ (v′) → X2Σg+ (v″).