Structural modifications caused by oxidation of the hot W(001) surface were investigated with complementary low-energy electron diffraction and microscopy. The surface initially accommodated oxygen up to 1.2ML coverage by passing through a sequence of closely related missing-row reconstructed structures, including (2 x 1), (5 x 1) and incommensurate (5 x 1) arrangements. An unusual nucleation behaviour of a p(2 x 1) penetrated oxide at 1.0ML was also observed and demonstrated by dark-field low-energy electron diffraction and microscopy to be due to preferential nucleation at domain walls of the underlying reconstructed surface. A relationship of the reconstructed domain morphology with percolation in two-dimensions was suggested by the domain fractal dimension, D=1.875, determined from low-energy electron diffraction and microscopic images. Growth of the p(2 x 1) and an additional p(2 x 2) oxide structure occurred rapidly on the reconstructed surface once it becomes oxygen-saturated at higher coverage.

LEEM/LEED Investigation of Reconstruction and Initial Oxidation of the W(001) Surface. M.S.Altman, E.Bauer: Surface Science, 1996, 347[3], 265-79