Double charge transfer spectroscopy for N22+ and CO2+ at vibrational resolution

Doubly charged molecular ions (dications) of N2 and CO have been studied using a double charge transfer (DCT) spectrometer capable of resolving vibrational levels. The vibrational structures of low-lying singlet states are observed in the translational energy spectra of H− ions produced by double electron capture collisions of H+ projectiles. The observed spectra are well reproduced using the theoretical Franck–Condon (FC) profiles calculated from the best available ab initio potential curves. This suggests that the DCT process obeys the FC principle, i.e., the vertical transition from a neutral molecule to the corresponding dication.