Mass analyzed threshold ionization spectroscopy of 2-aminopyridine cation

Mass analyzed threshold ionization (MATI) spectroscopy was used to record the cationic spectra of 2-aminopyridine (2AP) via the 00 vibrationless and the 6a1, 11, I2, and 18a1 vibrational levels of the S1 state. The adiabatic ionization energy of this molecule was determined to be 65 411±5 cm−1 (8.1095±0.0006 eV). The experimental findings show that the molecular geometry and vibrational features of the 2AP cation resemble those of the neutral species in the S1 state, which is well supported by the ab initio and density functional calculations.