Analysis of Na(4 × 4)/Al(1 1 1) with anharmonicity

Abstract SEXAFS of the low temperature Na 4 × 4 structure formed on Al(1 11) has been analysed using a least squares optimisation program. Without anharmonicity a rotated cluster model with a bond distance of 3.70 ± 0.4 A and an unrotated cluster give good agreement. Including an anharmonic contribution the close packed model, with NaNa bond length of 3.81 A is also a possible candidate. In all cases the nearest neighbour bond length is 2.65 ± 0.08 A .