Observation of X-Ray Diffraction Spots from the (\sqrt3×\sqrt3)R30° Bi Structure on the Si(111) Surface under the Condition of Large Incidence Angle

X-ray diffraction intensities from the (√3 ×√3)R30° Bi structure on the Si(111) clean surface were measured in an experimental geometry similar to that of LEED. Two diffraction spots of 1/3, 1/3 and 2/3, 2/3 were observed at the scattering angle of 133° for X-rays with the wavelength of 1.76 A. A silicon wafer about 5 µm thick was used to reduce the background scattering from the bulk crystal.