Mass analyzed threshold ionization of p-bromoaniline: heavy atom effects on electronic transition, ionization, and molecular vibration

We have recorded the vibrationally resolved spectra of p-bromoaniline in the S1 and cationic ground state. The band origin of the S1←S0 electronic transition is found to be 32 590±1 cm−1, whereas the adiabatic ionization energy is 62 308±5 cm−1. Most of the active vibrations of p-bromoaniline in the S1 and cationic ground states are related to the totally symmetric in-plane ring modes, as in aniline. Comparison among these new experimental data and those of aniline, p-fluoroaniline and p-chloroaniline offers a good understanding about the heavy atom effects on the electronic transition, ionization and molecular vibration. The experimental findings are well supported by the ab initio and density functional calculations.