The electronic spectrum of furan

The 30 lowest electronic states of furan have been investigated with theoretical calculations (up to approximately 8.3 eV), and the experimental spectrum scrutinized in the relevant energy region. Electron correlation effects have been examined by performing calculations in a hierarchy of coupled cluster models, and basis set effects have been investigated by carrying out calculations using extensive basis sets. The difference between vertical and adiabatic excitation energies have been calculated. Oscillator strengths, excited-state dipole moments, and second moments of the electronic charge distributions have been used to characterize the calculated electronic transitions and final states. Several reassignments of features in the experimental spectrum have been suggested.