An experimental and theoretical investigation into the excited electronic states of phenol

We present experimental electron-energy loss spectra (EELS) that were measured at impact energies of 20 and 30 eV and at angles of 90 degrees and 10 degrees, respectively, with energy resolution similar to 70 meV. EELS for 250 eV incident electron energy over a range of angles between 3 degrees and 50 degrees have also been measured at a moderate energy resolution (similar to 0.9 eV). The latter spectra were used to derive differential cross sections and generalised oscillator strengths (GOS) for the dipole-allowed electronic transitions, through normalization to data for elastic electron scattering from benzene. Theoretical calculations were performed using time-dependent density functional theory and single-excitation configuration interaction methods. These calculations were used to assign the experimentally measured spectra. Calculated optical oscillator strengths were also compared to those derived from the GOS data. This provides the first investigation of all singlet and triplet excited electronic states of phenol up to the first ionization potential. (C) 2014 AIP Publishing LLC.