Thermodynamic and structural study of methanol thin films adsorbed on MgO(1 0 0)

Thermodynamic and structural properties of methanol monolayer and multilayer films adsorbed on MgO(1 0 0) surface have been investigated by neutron diffraction and volumetric adsorption isotherms techniques. The form of the measured adsorption isotherms varies with the temperature range. At higher temperature isotherms are composed of two steps with equal height indicating the condensation of two layers with identical density. At lower temperature the formation of the previous two layers undergoes a succession of transitions. The neutron diffraction spectra, measured at θ=2 monolayers, show a strong commensurability of the CH3OH monolayer and bilayer films with the MgO(1 0 0) surface.