High-Resolution Calculations on Atom-Surface Scattering: Method and Comparison with Experiment for Ne/LiF

Abstract

Articles you may be interested inThe Ne-O2 potential energy surface from highresolution diffraction and glory scattering experiments and from the Zeeman spectrum J. Chem. Phys. 95, 195 (1991); 10.1063/1.461475The Ne-N2 potential energy surface from highresolution total differential scattering experiments and a closecoupling and infiniteordersudden analysis J. Chem. Phys. 89, 3505 (1988); 10.1063/1.454922Atom-surface scattering dynamics at hyperthermal energies Calculated scattering distributions for Ne on (001) LiF are compared with corresponding experimental distributions. For calculational purposes, the surface is effectively modeled by a monolayer of 3D harmonic oscillators representing F-ions. The atom-surface potential at close range is assumed to arise from twobody dispersion-exchange interactions which are represented by superposed Lennard-Jones (12, 6) model potentials. The foregoing potential is shown to be large with respect to that due to induced-dipole interaction. The long-range van der Waal's potential, for which the strength is independently specified, is taken to be one-dimensional in nature. The classical trajectory method combined with Monte Carlo distribution of surface impact coordinates and thermal states of gas/surface atoms is used to determine angular distributions of scattered beam intensity. Physical concepts underlying an efficient calculational algorithm required for high resolution scattering calculations are described. For a variety of incident beam conditions, including variation of beam "temperature," angle of incidence, and azimuth of the plane of incidence, calculated angular positions of dominant intensity peaks in the scattered beam typically agree with experimental determinations to within 3°_5°. Predictions of high intensity "ridge" structure, which is quite different in form for the (010) and the (110) planes of incidence, are confirmed by experimental studies undertaken elsewhere. Calculated values of absolute scattering probability in the plane of incidence typically agree with prior experimental determinations to within 10%-15%. Statistical fluctuations in the calculated intensities (",5%-10% of the calculated value) preclude a rigorous determination of whether or not the model reproduces all observed substructure on the high-intensity ridges. The parameters defining the semiempirical Ne/LiF potential used in the present study correspond to a heat of adsorption of "'0.016 eV, and to a two-body range parameter of 3.9 1. Means for determination of the potential parameters from a small part of the available experimental data and means for assessing the accuracy of these values are reported in a companion paper.

Selective adsorption resonances: Quantum and stochastic approaches

“…For example, classical trajectories have been used to study the manifestations of classical surface rainbows [105,[346][347][348][349] in quantum diffraction patterns [108,109,295,350,351]. Classical trajectories have also been used to compute the value of certain quantum-mechanical magnitudes by imposing a quantization condition on the count of trajectories.…”

Second-Order Semiclassical Perturbation Theory for Diffractive Scattering from a Surface

“…When dealing with heavy atoms as probe particles, classical features are very prominent and can shed light on surface properties. Rainbow features − in the final angular distributions are especially important because the angular distance between them is directly related to the surface corrugation. Their energy dependence is related to the physisorption well depth.…”

Atom–surface scattering in the classical multiphonon regime

“…However, for large projectile energies, the coherence length for quantum interference becomes negligibly small, and for an ordered surface the double integral can be replaced by integrals over a single unit cell, multiplied by the number of unit cells which is simply a large constant. In the special limiting case where the corrugation function x(R) is taken to be a constant, in other words, for a smooth flat surface, eqn (17) reduces to the result of eqn (14) for the smooth surface model.…”