On the nature of the rate limiting step of the reaction of interaction of monocrystalline germanium with gaseous bromine

Abstract

The characteristics of the interaction of a germanium monocrystal with bromine have been studied by means of kinetic and ellipsornetric methods. It is shown that the concentration dependence of the rate of the reaction is described by the kinetic equation W = KaP (1 + aP) f , and that the activation energy and pre-exponential factor are 33 ± 1 kcal/mol and 10 28±1 atoms/cm 2 sec, respectively. It is also established, with the help of ellipsomerty and laser photochemistry, that the main product of the reaction at temperatures below 300°C is GeBr 4. Two layers of adsorbed bromine molecules on the germanium surface are needed to form GeBr 4. The experimental data make us conclude that the rate-limiting step of the process is chemical transformation of the surface of the adsorption complex (>GeBr 2 · Br 2 ads into the adsorbed product of the reaction (GeBr 4) ads.