Jonathan V. Caspar

Mechanistic aspects of the photochemistry of metal-metal bonds. Evidence for the intervention of two different primary photoproducts in the photochemistry of (eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/Fe/sub 2/(CO)/sub 4/

The photochemistry of the iron dimer (eta/sup 5/-C/sub 5/H/sub 5/)/sub 2/Fe/sub 2/(CO)/sub 4/ was investigated by flash photolysis under both net photochemical and nonphotochemical conditions in inert solvents, cyclohexane and benzene. Under nonphotochemical conditions, the compounds were found to be completely photochromic and stable for a period of at least several weeks. Either uv of visible flash-photolysis of the dimer was found to lead to two intermediates, which were both present immediately following the flash. However, each specie was found to occur at a different rate and could be studied separately. The shorter lived intermediate was found to return to the original dimer by equal concentration, second-order kinetics within 2 ms after the flash. The longer lived species also returned to the original dimer but by first-order kinetics. Results of studies of the reactivity with added substrates are also reported. (BLM)

Application of the energy gap law to the decay of charge transfer excited states, solvent effects

Abstract Values of non-radiative decay rate constants (knr) and emission energies (Ecm) have been obtained for Os(Phen3)2+ in a series of solvents and the results are consistent with the energy gap law. For hydroxylic solvents like water or methanol related studies suggest the existence of strong, specific contributions to the vibrational trapping energy of the solvent.

Characterization of CZTSSe photovoltaic device with an atomic layer-deposited passivation layer

We describe a CZTSSe (Cu2ZnSn(S1−x,Sex)4) photovoltaic (PV) device with an ALD (atomic layer deposition) coated buffer dielectric layer for CZTSSe surface passivation. An ALD buffer layer, such as TiO2, can be applied in order to reduce the interface recombination and improve the devices open-circuit voltage. Detailed characterization data including current-voltage, admittance spectroscopy, and capacitance profiling are presented in order to compare the performance of PV devices with and without the ALD layer.