Ionization energy of o-fluoroaniline and vibrational levels of o-fluoroaniline cation determined by mass-analyzed threshold ionization spectroscopy

Mass-analyzed threshold ionization (MATI) and two-color resonant two-photon ionization methods were used for the determination of the ionization energ y (IE) of o-fluoroaniline (OFA) and the vibrational levels of the OFA catio n. The MATI spectra were recorded via the 0(0) vibrationless and the 10b(1) , 16a(1), 1(1) and 12(1) vibrational levels of the S-1 state. The adiabatic IE of OFA was found to be 63 644 +/- 5 cm(-1) (7.8904 +/- 0.0006 eV) by MA TI spectroscopy. The observed vibrations of the OFA cation include the in-p lane ring CCC bending, CH bending, CF bending, CN bending and CN stretching , as well as some out-of-plane ring vibrations. The experimental findings a re well supported by ab initio and density functional theory calculations.