X-RAY-DIFFRACTION STUDY OF LIQUID NEOPENTANE IN THE TEMPERATURE RANGE 17 TO 150 DEGREES-C

The x-ray diffraction pattern of liquid neopentane has been measured at eight different temperatures between the melting point (-17°C) and the critical point (161°C). In the data analysis, the methyl groups were treated as single scattering centers, and the molecular structure derived from the large-angle part of the x-ray data was found to be the same as that found for the low density vapor. Subtraction of the molecular structure yields a set of distinct structure functions descriptive of intermolecular atom pair correlations. It is shown that a realistic model for the orientational correlations between molecules in the liquid must reproduce the experimental structure functions beyond the first maximum. The radial distribution functions derived from the data indicate well defined Me⋯Me contacts between neighboring molecules at low temperature (high density). © 1979 American Institute of Physics.