On the electronic spectroscopy of the iso-polyhalomethanes

► Theory and multi-dimensional Franck-Condon (FC) analysis of electronic spectra of iso-polyhalomethanes. ► Intense S0 → S3 transition is best described as a π-π∗ transition localized on a halocarbocation chromophore. ► Significant geometry changes induced upon electronic excitation. ► Calculated multimode FC profiles capture important features of the experimental spectra of the matrix-isolated species. ► Good agreement with results of previous Resonance Raman studies of the isomers in solution.