STM observation of steps and terraces on tungsten (211) surface.

Thermally cleaned W(211) surface with 0.7 degrees miscut consists of (211) terraces separated by monoatomic steps. When the surface is exposed to oxygen and subsequently annealed at 1100-1900 K, the width of (211) terraces increases and multilayer steps are formed. Similar step bunching is observed during routine cleaning of the sample by annealing in oxygen and thermal flashing in ultra high vacuum. During such cleaning procedure islands of c(6 x 4) reconstruction are observed.