Structures of the 'nanowire' and 2 x n phase of the submonolayer system of
Bi/Si(001) have been studied by X-ray photoelectron diffraction (XPD). The
general features of Bi 4d XPD patterns show that Bi atoms exist only at the
topmost layer for the two phases. Single-scattering cluster simulations we
re performed for several structural models, including those for the 'nanowi
re' [Miki et al., Phys. Rev. B 59 (1999) 14 868] and for the 2 x n phase [H
anada et al., Surf. Sci. 242 (1991) 137], to find they are very feasible. (
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