Species-selected mass-analyzed threshold ionization spectra of m-fluoroaniline cation

Two-color resonant, two-photon mass-analyzed threshold ionization (MATI) spectroscopy was used to probe the ionic properties of m-fluoroaniline (MFA), The species selection from a mixture was achieved by tuning the frequency of the excitation laser to a specific intermediate level of MFA for the successive excitation, followed by pulsed field ionization. The MATI spectra were recorded by ionizing via the 0(0) vibrationless and the 4(1), 15(1), and 9b(1) vibrational levels in the S-1 state. The adiabatic ionization energy of MFA was determined to be 64 159 +/- 5 cm (1) (7.9542 +/- 0.0006 eV). Analysis of the spectral features shows that the active modes of the ion are closely related to the specified vibrations of the neutral. These findings indicate that the geometry of the ion is quite similar to that of the neutral in the S-1 state.