Rotamers of m-chloroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy

Abstract

We apply the resonant two-photon ionization (R2PI) and mass-analyzed threshold ionization (MATI) techniques to record the vibronic and cation spectra of m-chloroanisole. The vibronic features appear in two series, built on 35,822±2 and 35,868±2cm−1, corresponding to the origins of the S1←S0 electronic transition (E1’s) of the two rotamers. Analysis of the MATI spectra gives the adiabatic ionization energies (IEs) of 67,645±5 and 68,008±5cm−1 for these two isomeric species. Comparing these data with those of anisole, we find that the chlorine substitution at the meta position leads to a red shift in the E1 and a blue shift in the IE. The observed R2PI and MATI bands mainly result from the in-plane ring deformation and substituent-sensitive bending vibrations of these species in the electronically excited S1 and cationic ground D0 states.