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Angle-resolved ultraviolet photoelectron spectra have been measured for well defined Ag/Si(111) submonolayer interfaces of (1) Si(111)( 3 × 3 )R30°-Ag , (2) “Si(111)(6 × 1)-Ag”, and (3) Ag/Si(111) as deposited at room temperature. Non-dispersive and very narrow (FWHM ∼ 0.4–0.5 eV) Ag 4d derived peaks are found at 5.6 and 6.5 eV below the Fermi level for surface (1) and at 5.3 and 6.0 eV for surface (2). Dispersions of sp “binding” states in the energy range between E F and Ag 4d states have been precisely determined for surface (1). Electronic structures similar to those of the Ag(111) surface, including the surface state near E F , have been observed for surface (3).

He + impact collision ion scattering spectroscopy (ICISS) has been applied to the Ge(111)c(2 × 8). Ge(111)7 × 7−Sn. 5 × 5−Sn. and 3 × 3 −Sn surfaces. For the Sn-covered Ge(111) surfaces, it has been found that most Sn atoms occupy top portions of the Ge surfaces. From comparisons of computer simulation for ICISS curves with experiment, it has been concluded that trajectory-dependent neutralization of He + denies a simple view of shadowing and focusing of He + usually assumed in ICISS.