Disorder versus structure analysis in intergrowth urea inclusion compounds

Alkane/urea inclusion compounds constitute a class of incommensurate composite materials, characterized by a pronounced one dimensional character and strong disorder of the alkane molecules. Intrinsic features of the alkane molecular form factor can be used to obtain a quantitative interpretation of the alkane subsystem translational degree of freedom whereas they lead to the restriction of observable Bragg reflections. A rigid body approach is also presented, which gives a simple description of the alkane sublattice modulation in the frame of (3 + 1) dimensional structure refinement.