Electronic structure of layered silver carboxylates

A series of silver salts of straight-chain organic monoacids, [CH3(CH2)nCO2Ag]2, and diacids, Ag[O2C(CH2)nCO2Ag]m, have been prepared. Powder deposits of these layered organic dielectric sandwich-type solids have been characterized by reflection spectroscopy. From analysis of the absorption edges we infer in all cases an indirect optical band gap. For interlayer spacings, d⩽30 Å (n⩽10), superlattice formation occurs with concomitant redshift in the absorption edge, by 0.135 eV (∼10 nm) for the limiting monoacid case, n=0. These results have been rationalized by tight-binding band-structure calculations from the literature and by a fragment orbital in the solid calculation at the extended Hückel level of approximation.