Surface states on clean (100), (110) and (111) surfaces were studied by means of angle-resolved UV photo-electron spectroscopy with unpolarized light. Surface states on (110) and (111) were observed for the first time, and the energy-band structures were determined. The surface states on (110) were located at ∼1.8 and ∼3.0eV below EF. They were associated with the occurrence of the c(2 x 2) surface structure on (110). The surface states on (111) were located at ∼1.5 and ∼2eV below EF. The dispersion of the lower band was relatively large (∼0.9eV) compared with those on (100) and (110). The surface state at ∼2eV below EF on (111) had a maximum energy at the Γ point (k∥ = 0), while that on (100) had a minimum energy at the Γ point. The surface state at ∼2eV below EF on (100) had Δ1 symmetry at k∥ = 0, and had even parity with respect to the (010) and (011) planes. A low-lying surface state on (111) had Δ1 symmetry at k∥ = 0. All of these surface states on the clean surfaces were interpreted in terms of dangling bonds of the surface boron frameworks which were mainly B 2p in character.

Surface States on the LaB6(100), (110) and (111) Clean Surfaces Studied by Angle-Resolved UPS. Nishitani, R., Aono, M., Tanaka, T., Kawai, S., Iwasaki, H., Oshima, C., Nakamura, S.: Surface Science, 1980, 95[2-3], 341-58