Mass analyzed threshold ionization spectroscopy of p-methylanisole cation and the substitution effect

The adiabatic ionization energy of p-methylanisole is measured to be 63 972 ± 5 cm−1, which is red-shifted with respect to those of anisole and toluene. This indicates that the interaction of either CH3 or OCH3 group with the ring is stronger in the cationic D0 state than that in the neutral S0 state. Most of the observed MATI bands result from in-plane ring vibrations. The frequencies of vibrations 9b, 6a, and 1 of the p-methylanisole cation are found to be 407, 515, and 811 cm−1, respectively.