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

Abstract

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.