Resonance enhanced multiphoton ionization and mass analyzed threshold ionization spectroscopy of 4-fluorobenzonitrile

Abstract The vibrational features of 4-fluorobenzonitrile in the first electronically excited state S 1 and cationic ground state D 0 have been studied by two-color resonance enhanced multiphoton ionization and mass analyzed threshold ionization spectroscopy. Most of observed vibrations in the S 1 and D 0 states are related to in-plane ring deformation and CN bending motions. The band origin of the S 1  ← S 0 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.