X-Ray Determination of the Structure of Liquid Methane

X-ray diffraction measurements from liquid methane at four conditions of temperature and pressure ranging from near the triple point to the critical point indicate a structure of molecules in the liquid resembling close packing of spheres. The first peaks in the density functions are asymmetric and have areas and positions which range from 11.4 nearest neighbors at 4.24 angstrom and 96 degrees K to 7.2 nearest neighbors at 4.35 angstrom and 186 degrees K. The methane x-ray form factor is derived from gaseous scattering experiments.