Laser-pulse photocurrent transient measurements at oxygen evolving n-PtS2

Laser-pulse transient measurements have been performed at single crystalline n-PtS₂ electrodes with the aim of understanding light-induced hydroxide, oxide and oxygen formation. Different detected time constants permit the identification of distinct reaction products. They form surface states which function both as centers for recombination and charge accumulation in the interface. The rate constants determined are influenced by the RC-constant of the measuring circuit and can be interpreted only qualitatively. In the presence of recombination processes time constants faster than R_LC_SC are found. Evidence is given that the reaction step leading to oxygen evolution is dependent on the building-up of an electric field in the Helmholtz layer. This result may be of importance for the development of materials for the photoelectrolysis of water.     

Boat and chair benzenes incorporated in cyclophanes

Various modes of the out-of-plane deformation of a benzene ring have been examined theoretically the MINDO/2 methods. Deformation to the boat conformation is predicted to be more facile than that to the half-boat or the chair conformation as observed in triple-layered[2.2]-metacyclophanes. The energy partitioning analysis reveals that a minimal loss of resonance energy at the gunwale of benzene boats appears to be responsible for the ease of boat deformations. The out-of-plane bending of the H atom at the bow of die benzene boats is coupled to the displacement of the H at the gunwale in such a way that the torsion of the bond between the bow and gunwale C atoms may be kept as small as possible.     

Cluster configuration method: application to the spectra of π-electron systems

A simplified method to calculate the excitation spectra of π-electron systems is proposed. The method is based on the assumption that a “cluster” approximation can be applied to excited states. It is demonstrated that, for the low-lying triplet and optically allowed states of butadiene, hexatriene and benzene, the method yields good agreement with complete CI calculations in the Pariser–Pan–Pople approximation.     

Application of multiconfigurational many-body perturbation theory to the calculation of ionization potentials,electron affinities and excitation energ

Multiconfigurational many-body perturbation theory is applied to the problem of calculating ionization potentials, electron affinities, and excitation energies. H₂O, C₂H₄, and H₂ are studied, with correlation corrections through third order and inclusive of certain higher-order terms. Results are compared with those by other many-body theoretical methods.