Amorphous nearest-neighbor distance

Calculate the average nearest neighbor distance for the amorphous polymer sample. 

Correlation functions hoo(R) for the amorphous deposit prepared and studied at 77 K are shown in Fig. 7b together with the curve for polycrystalline ice Ih. As in the crystalline phase, the nearest-neighbor oxygen-oxygen correlations in H20(as) occur in an exceptionally narrow band centered at 2.76 A, with rms-deviation 0.114 A. The distance ratio for second and first neighbors indicates tetrahedral coordination on the average, but the second neighbor peak near... 

X-ray studies also suggest the presence of order. Intensity maxima of 0.126, 0.223, 0.478, and 0.9-1 nm were obtained with amorphous polystyrene, for example. The value 0.126 nm corresponds to the normal distance between two neighboring carbon atoms in the chain. The value 0.223 nm is approximately the distance between one main-chain carbon atom and its next nearest neighbor. The value of 0.478 nm is also observed with monomeric styrene. It is displaced to higher values with increasing cross-linking and consequently must refer to an intermolecular distance. 

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