Two-color resonant two-photon ionization and mass-analyzed threshold ionization spectroscopy of o-chloroanisole

We applied the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibrationally resolved spectra of the selected isotopomers of o-chloroanisole in the electronically excited S1 and cationic ground D0 states. As supported by our theoretical calculations, only the trans form of o-chloroanisole involves in the two-photon photoexcitation and ionization processes. The band origins of the S1 ← S0 electronic transition and adiabatic ionization energies for the 35Cl and 37Cl isotopomers of o-chloroanisole are found to be the same within our detection limit, with the values of 35 745 ± 2 and 66 982 ± 5 cm−1, respectively. The general spectral features of the two isotopomers are nearly identical and result from in-plane ring deformation and substituent-sensitive bending and stretching as well as the CH3 torsional motions.