Random Occupation of Adsorption Sites in thec(2×2)Structure of CO on Fe{001}

A low-energy electron-diffraction intensity analysis of the Fe{001} $c(2\mathrm{}\times 2)$-CO structure confirms the results of photoemission studies by other workers suggesting dissociation of the CO molecule. The data are fitted well by a model with random occupation of fourfold symmetrical sites by carbon and oxygen atoms in a $c(2\mathrm{}\times 2)$ configuration, similar to that proposed earlier by Felter and Estrup and by Riwan, Guillot, and Paigne for Mo{001} $c(2\mathrm{}\times 2)$-CO.