Physical processes in coadsorption of oxygen and carbon on the W(100) surface: influence of atomic carbon dissolved in the bulk

Interaction between atomic oxygen and carbon on the W(100) surface is being considered in the wide range of temperatures (300 - 2000 K) and concentrations of both adsorbates. Oxygen atoms do not dissolve in the substrate bulk and leave the surface in the form of CO molecules. In the case of initially pure tungsten bulk and at oxygen and carbon coverage ϑ ≈ 0.5 these atoms peacefully coexist on the surface without forming CO molecules up to T ∼ 1050 K; at higher temperatures C atoms are displaced from the surface into the bulk, in the dissolved state. At T > 1400 K, the dissolved carbon atoms come to the surface, forming CO molecules with adsorbed oxygen which are desorbed. Complete purification of the surface is achieved at 1600 K. Carbon atoms predissolved in the tungsten bulk significantly influence the processes of CO molecules formation. In the presence of C atoms preliminary dissolved in the tungsten bulk, the reaction of CO formation with subsequent desorption starts at 800 K, and complete oxygen removal is observed at 1200 K.