A re-interpretation of the UV-photoelectron spectra of dewar benzene, norbornadiene and barrelene by ab initio configuration interaction calculations

Abstract

Ab initio configuration interaction calculations of the ground and cationic states of Dewar benzene, norbornadiene and barrelene have enabled a firm assignment of the uv-photoelectron spectra in the range 8–16 eV to be made. Many of the states are of Koopman's one-electron process type, and the order of states is close to that of the SCF double zeta ground state calculations. A number of shake-up doublet states were computed, and for barrelene at least, these appear from about 12 eV onwards; the lowest lying triplet and singlet states for barrelene were computed at 3.82 and 6.04 eV, respectively, and most of the low-lying shake-up states are related to this HOMO—LUMO pair of transitions.