Mass analyzed threshold ionization spectroscopy of anisole cation and the OCH3 substitution effect

The mass analyzed threshold ionization spectra of anisole have been recorded by ionizing via four vibronic states. The adiabatic ionization energy of this species is determined to be 66 399 ± 5 cm−1, which is lower than that of benzene by 8158 cm−1. This indicates that the interaction of the OCH3 with the phenyl ring is stronger in the cationic D0 than that in the neutral S0 state. Most of the observed active vibrations of the cation result from the in-plane ring vibrations and substituent-sensitive modes.