X-RAY-DIFFRACTION STUDY OF THE STRUCTURE OF A MONOLAYER METHANOL FILM ADSORBED ON GRAPHITE

The x-ray diffraction measurements of methanol adsorbed on graphite have been taken over the temperature range 32-150 K and the coverage range 0.02-0.17 molecule Å-2. The diffraction data are analyzed to yield the configuration of the molecule on the surface by means of the least-squares fitting of the whole pattern. The data show clearly that zigzag chains of alternating weak and strong hydrogen bonds, as evidenced by the long and short 0⋯0 separations, are formed in the crystalline monolayer of methanol on graphite. The crystalline solid film near the complete monolayer melts around 142 K in comparison to bulk methanol which melts at 175.4 K. © 1990 American Institute of Physics.