The difference in the extent of interdigitation between 8OCB and 9 suggests that the interlayer boundary at the tail end of these molecules is more clearly defined for 9 than 8OCB. This effect is shown clearly by the snapshots in Figure , which show the positions and orientations of the five terminal carbon atoms of the alkyl chain of 8OCB and the equivalent carbon atoms of 9. For 8OCB, there is clear interdigitation between the alkyl chains of the molecules pointing up and down, and the associated alkyl layers are diffuse. For 9, not only are the alkyl layers more defined, but the inter-layer boundary shows two almost distinct sublayers arising from the separation of cyclohexyl groups in molecules pointing up and down.