Experimental in situ studies of copper exposed to humidified air

Three complementary experimental techniques for in situ surface analysis ha ve been combined for the first time in order to explore the chemistry and p hysics of a copper surface exposed to humidified air. Infrared reflection a bsorption spectroscopy, quartz crystal microbalance and atomic force micros copy provide a congruent picture of the processes occurring at the surface. At a given relative humidity, cuprous oxide forms according to an approxim ately logarithmic rate law. In addition, an aqueous adlayer of constant mas s physisorbs on the surface. Increased relative humidity stimulates the phy sisorption of water and enhances the nucleation rate of oxide grains, there by increasing the formation rate of cuprous oxide. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.