Sm. Clarke et al., CLOSE PACKING IN 2D LAYERS - THE STRUCTURE OF A CIS-1,2 DICHLOROETHENE MONOLAYER ON GRAPHITE, Acta chimica Hungarica, 130(3-4), 1993, pp. 441-449
Preliminary results are presented for a single crystalline phase of ci
s-1,2 dichloromethane monolayer adsorbed on graphite. No evidence was
found of other phases before bulk condensation sets in. A possible str
ucture for this adsorbed layer is proposed, determined by X-ray diffra
ction measurements. The experimentally determined unit cell is incomme
nsurate with respect to the underlying substrate and rectangular, with
lattice parameters a = 11.91 angstrom, b = 5.36 angstrom and nu = 90-
degrees. There are two molecules per unit cell arranged to give chains
with space group cm, and all the molecules lie approximately flat on
the surface. The 2D packing coefficient of the layer is determined to
be 0.91, the same as the value expected for close packed spheres (0.91
). The structure of this monolayer is discussed with respect to the cl
ose packing arguments of Kitaigorodskii.