ANALYSIS OF THE (3 × 3)-H/Cu(111) SYSTEM USING EIKONAL-LEVEL HELIUM ATOM SCATTERING SIMULATIONS

The saturated (3 × 3)- H / Cu (111) system has been investigated by Eikonal-level helium atom scattering (HAS) simulations of previously reported HAS diffraction images. Basing the investigation on an unreconstructed single-domain structure with H atoms occupying three-fold hollow adsorption sites, a systematic trial of all possible structures has been performed and a series of structures has been shown to agree with the experimental images. Comparison of this fitting process to diffraction images taken at low (30°) and high (47°) angles of incidence has shown that the Eikonal approximation is a reasonable scattering algorithm for the H / Cu (111) system.

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DEVELOPMENT OF DIRECT METHODS OF DATA INVERSION IN HELIUM ATOM SCATTERING

Surface Review and Letters ◽

10.1142/s0218625x07009426 ◽

2007 ◽

Vol 14 (02) ◽

pp. 321-327 ◽

Cited By ~ 4

Author(s):

I. G. SHUTTLEWORTH

Keyword(s):

Helium Atom ◽

Eikonal Approximation ◽

Direct Methods ◽

Real Space ◽

Simultaneous Equations ◽

Space Structures ◽

Diffraction Image ◽

Helium Atom Scattering ◽

Data Inversion ◽

Atom Scattering

The problem of diffraction pattern deconvolution in Helium Atom Scattering (HAS) has been solved directly within the Eikonal approximation. A formulation based on the Patterson construction has been developed which reduces the problem to the solution of a set of simultaneous equations in {ζj}, where ζj are the corrugation parameters for the surface. The formulation returns real space structures that satisfy unitarity, a secondary problem in HAS diffraction image inversion. Numerical benchmarks of this procedure are presented.

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STUDIES OF THE ADSORPTION OF CYANOGEN (C2N2) ON Cu(001) USING HELIUM ATOM SCATTERING

Surface Review and Letters ◽

10.1142/s0218625x07010330 ◽

2007 ◽

Vol 14 (05) ◽

pp. 863-872 ◽

Cited By ~ 3

Author(s):

I. G. SHUTTLEWORTH

Keyword(s):

Domain Structure ◽

Helium Atom ◽

Ordered Structure ◽

Strain Relief ◽

Helium Atom Scattering ◽

Disordered Structure ◽

Atom Scattering ◽

Disordered Phase ◽

Plane Diffraction ◽

Kontorova Model

The adsorption of cyanogen ( C 2 N 2) on Cu (001) has been investigated using helium atom scattering. Adsorption at 263 K produces a two domain structure with periodicity c(10 × 6) and symmetry c2 mm. The principle axes of the two domains in the c(10 × 6) pattern lie at right angles to one another. Adsorption at lower temperatures (163 K) produces a disordered structure with no observable diffraction features other than the specular. Annealing the disordered phase to 263 K does not produce an ordered structure. Cooling the ordered structure from 263 K to 163 K produces an enhancement of the diffraction features consistent with the Debye–Waller effect but no disruption of the c(10 × 6) periodicity. Annealing the ordered structure shows that the structure remains stable at temperatures up to 373 K. Analysis of the in-plane diffraction features suggests a reconstruction of the Cu (001) substrate consistent with the 2D Frenkel–Kontorova model for overlayer strain relief.

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