STRUCTURE OF THE OXYGEN MONOLAYER ON THE BASAL-PLANE OF ZINC SINGLE-CRYSTALS

Using the low-temperature reflection high energy electron diffraction we have studied the structure of the oxygen layer, chemically sorbed o n the basal surface of a Zn single crystal. The nearest neighbor dista nce within the oxygen layer, as a function of temperature, exhibits an anomaly in the range 120 to 130 K, which we ascribe to a change in th e commensurability of the oxygen layer and the zinc surface. The anoma ly is reversible in temperature. Analysis of diffraction patterns for relatively rough samples shows that the relaxation of the Zn surface l ayer is contractive by about 8 %.