2 NEW OXYGEN INDUCED RECONSTRUCTIONS ON CU(111)

The chemisorption of oxygen on Cu(111) has been studied by means of STM, HEIS, NRA and AES. Our STM studies have identified two new well ordered oxygen induced reconstructions with large cells, 29 and 44 times larger than the (1 x 1) unit cell. From an NRA investigation of the "29"-structure, it is found that the oxygen coverage is 0.52 +/- 0.05 monolayer (ML), whereas the surface peak, measured by means of HEIS at normal incidence, increases by 1.03 +/- 0.1 ML going from the clean to the oxygen saturated surface. Based on these observations, it is proposed that the reconstructions emerge as coincidence lattices between the (1 x 1) lattice and a hexagonal substructure associated with the (111) plane of Cu2O.