Abstract The excited electronic states of 2, 2-dimethylisoindene (1) have been studied by electron-energy-loss spectroscopy. Its vertical gas-phase triplet (1 3 B 2), and singlet (1 1 B 2) excitation energies are 1.61 and 3.19 eV, respectively. The excited states are thus lowered by 0.49 eV and 1.21 eV, respectively, when compared to the corresponding states of (all-E)-octatetraene, which serves as a reference compound. These shifts are partially ...
