The Formation and Spectroscopic Manifestation of Inorganic Clusters on Silver Bromide Interfaces Alfred Marchetti The photographic process is enhanced by treating the silver halide (AgX) microcrystals, that is micrometer sized crystals of AgCl, AgBr or AgBr/I, with labile sulfur and or gold compounds or with reducing agents. It has been shown that these materials deposit sulfur, gold or silver centers on the surface of the silver halide microcrystal surface. It is generally thought that any one treatment may produce several different 'clusters'. We have used a combination of low temperature photoluminescence, magnetic resonance and computational techniques to elucidate the structure and photophysics of a number of these small inorganic clusters.