Mass analyzed threshold ionization spectroscopy of 7-azaindole cation

The vibrationally resolved mass analyzed threshold ionization (MATI) spectra of jet-cooled 7-azaindole have been recorded by ionizing via four different intermediate levels. The adiabatic ionization energy of this molecule is determined to be 65 462±5 cm−1, which is greater than that of indole by 2871 cm−1. The vibrational spectra of 7-azaindole in the S1 and D0 states have been successfully assigned by comparing the measured frequencies with those of indole as well as the predicted values from the ab initio calculations. Detailed analysis on the MATI spectra shows that the structure of the cation is somewhat different from that of this species in the neutral S1 state.