Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of the 35Cl and 37Cl isotopomers of p-chloroanisole

► Resonance-enhanced multiphoton ionization spectra of the 35Cl and 37Cl isotopomers of p-chloroanisole have been firstly obtained. ► The S1 ← S0 electronic transition energies of 35Cl and 37Cl isotopomers were found to be equivalent at 34 859 ± 3 cm−1. ► Assignments of the observed vibrational bands of the two isotopomers were made mainly based on the CIS/cc-PVDZ calculations and on conformity with the available data in the literature. ► The isotope effect on vibrational frequency partially depends on the degree of involvement of the chlorine atom in the molecular vibrations.