The structure of the c(4 x 2) CO/MgO(001) monolayer revisited by neutron diffraction

Neutron diffraction experiments on the CO monolayer adsorbed on MgO(0 0 1) below 40 K are performed to complement information already available from low energy electron diffraction, thermal helium atom scattering and infrared spectroscopy. Revisited configurations for the c(4 x 2) monolayer containing 6 molecules per unit cell, equivalent by two, are discussed on the basis of a semi-empirical potential already presented in previous papers. The fit of the diffraction spectrum calculated for some stable configurations of the monolayer with the experimental neutron diffraction spectrum shows the best agreement for a dissymmetric geometry not considered previously. (C) 2001 Elsevier Science B.V. All rights reserved.