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The composition and structure of an InP{100} surface in both the (1 × 1) and the reconstructed (4 × 2) phases, prepared by ion bombardment and annealing, have been examined by time-of-flight scattering and recoiling spectrometry (TOF-SARS) and low-energy electron diffraction (LEED) . Time-of-flight spectra of scattered and recoiled neutrals plus ions were collected as a function of crystal azimuthal rotation angle δ and primary beam incident angle α. Compositional analyses of the surfaces were obtained from 4 keV Ar+ scattering and recoiling spectra. Structural analyses of the phases were obtained from the azimuthal anisotropy of the δ-scans and the features of the polar incident α-scans using 4 keV Ne+ scattering from In atoms and 4 keV Kr+ for recoiling of P atoms. These azimuthal δ-scans and incident a-scans were simulated by means of a shadow cone focusing model and a modified version of the MARLOWE code, respectively. The totality of this data leads indubitably to a model in which every fourth In 〈011〉 row is missing, the In atoms are trimerized along the 〈011〉 azimuth, and the 2nd-layer P atoms exposed in the 〈011〉 troughs are dimerized. This In missing-row-trimer P dimer model (MRTD) is consistent with all of the data, is autocompensated, and has In intratrimer spacings of 3.65 ± 0.20 A and P intradimer spacings of 2.95 ± 0.20 A. The results of the simulations suggest that the two end In atoms of the trimers are relaxed downward by a minimum of 0.15 A. Two other models were considered: (1) An In missing-row (MR) model without trimers or dimers in which every fourth In 〈011〉 row is missing. (2) An In missing-row-dimer (MRD) model, similar to that proposed for the GaAs (4 × 2) structure, in which every fourth In 〈011〉 row is missing and In dimers form along 〈011〉. These MR and MRD models are inconsistent with large portions of the experimental data and the simulations.

Depth profiling of 200 A Al thin films on Si substrates is performed experimentally using oxygen in the ion beam source or in the analysis chamber. These depth profiles are also obtained by dynamic Monte Carlo simulation. In addition to the simulation of the ballistic cascade development, the computer code also includes additional chemically guided atomic relocation mechanisms. The comparison between experiment and simulation on the one hand, and between the two profiling methods on the other yields information about the target modification induced by the use of reactive species.

Computer simulation of the reflection of a keV ion beam from a single crystal is carried out for different target temperatures. Ar ions bombarding obliquely a Cu lattice with 2 keV, and a Ni crystal with 30 keV energy are considered. The potentials used are of Born-Mayer ( A e −r/b ) and Firsov ( Br −2 ) type respectively. Uncorrelated thermal vibrations of atoms with Gaussian distribution of their displacements are taken into account. The spatial and energy distribution of the reflected ions obtained for different temperatures are discussed. The energy spectra are compared with the experimental data for the same conditions.