STRUCTURE SENSITIVITY OF SCATTERED NE+ ION FRACTIONS FROM A NI(100) SURFACE

The incident, alpha, and azimuthal, delta, angle dependence of the sampling depth and scattered ion fractions for 4 and 8 keV Ne+ scattering from a clean Ni{100} surface have been investigated. Time-of-flight techniques are used for velocity analysis of both neutrals (N) and ions (I). Spectra of N + I and N (obtained by electrostatic deflection of I) allow determination of scattered Ne+ ion fractions as Y = [(N + I) - N]/(N + I). The results show that (i) the ion fractions exhibit a strong dependence on alpha and delta, (ii) the critical incident angle-alpha-c used in structure determinations is dependent on the type of scattering spectra collected, i.e., N + I or I only, and (iii) layer-specific information can be obtained by a judicious choice of alpha and delta.