2004 Volume 2 Pages 141-145
The energy contour at Fermi level (Fermi surface) of the Si(111)√3×√3-Ag superstructure was measured in several surface Brillouin zones (SBZs) by high resolution angle-resolved photoemission spectroscopy (ARPES). Fermi rings centered at Gamma points were observed only in the second SBZs, but missing in the first SBZ. This phenomenon was successfully reproduced by a calculation of the optical transition matrix based on a simple tight-binding approximation for the surface topmost-layer Ag atoms; the intensity in the first SBZ is diminished by destructive interferences in the matrix elements ( i.e., photoemission structure factor). Thus with the known atomic orbital components of the surface structure, we can predict the photoemission intensity distribution and correctly understand the band structure. [DOI: 10.1380/ejssnt.2004.141]