LIF excitation spectra for S0 → S1 transition of anthranilic acid: Detailed studies

Harmonic and anharmonic frequencies of vibrational modes were calculated using the HF/6-31G∗∗ and CIS/6-31G∗∗ methods for the S0 and S1 state, respectively. Modelling of band intensities using displacement parameters derived from the results of the ab initio calculations was performed. This modelling significantly underestimates the displacement parameters. The Dushinsky matrix derived from the results of the ab initio calculations was used to check the validity of the models and to find modes which undergo large frequency changes and mode mixing upon electronic excitation.