Photoelectron-diffraction study of ultrathin films of AgBr on Ag(111)

Angle-resolved photoemission from the core levels of Br has been used to study the Stranski-Krastanov layer which precedes the growth of islands for molecular-beam epitaxy of AgBr onto Ag(111). Experimental results are compared with a spherical-wave theory of the differential cross section for photoemission using local clusters of Br and Ag ions consistent with low-energy electron-diffraction observations. The results favor one of three possible models in which the bromine atoms occupy threefold hollow sites on the substrate in a honeycomb structure. Half of the deposited silver atoms fill open spaces in this network and half reside outermost on top of the bromine to form a centered-hexagonal network, which fits in with the formation of strained layers of (111) AgBr as islands form. Suggestions are made for future work