Ms. Altman et E. Bauer, LEEM LEED INVESTIGATION OF RECONSTRUCTION AND INITIAL OXIDATION OF THE W(001) SURFACE/, Surface science, 347(3), 1996, pp. 265-279
Structural modifications caused by oxidation of the hot W(001) surface
have been investigated with complementary low energy electron diffrac
tion (LEED) and microscopy (LEEM). The surface initially accommodates
oxygen up to theta = 1.2 monolayer (ML) coverage by passing through a
sequence of closely related missing-row reconstructed structures, incl
uding (2 x 1), (5 x 1) and incommensurate (5 x 1) arrangements. An unu
sual nucleation behaviour of a p(2 x 1) penetrated oxide at theta = 1.
0 ML is also observed and demonstrated by dark-field LEEM to be due to
preferential nucleation at domain walls of the underlying reconstruct
ed surface. A relationship of the reconstructed domain morphology with
percolation in two-dimensions is suggested by the domain fractal dime
nsion, D = 1.875, determined from LEEM images. Growth of the p(2 x 1)
and an additional p(2 x 2) oxide structure occurs rapidly on the recon
structed surface once it becomes oxygen-saturated at higher coverage.