LAUSR

Abstract The vibrational features of 4-fluorobenzonitrile in the first electronically excited state S1 and cationic ground state D0 have been studied by two-color resonance enhanced multiphoton ionization and mass analyzed threshold ionization spectroscopy. Most of observed vibrations in the S1 and D0 states are related to in-plane ring deformation and CN bending motions. The band origin of the S1 ← S0 transition and adiabatic ionization energy of 4-fluorobenzonitrile are determined to be 36,616 ± 2 and 78,000 ± 5 cm−1, respectively. These data provide insight into the substitution effect of fluorine atom and cyano group on the transition energy.