Structural studies of tetrachloride liquids

The differential cross-sections for neutron scattering from liquid carbon tetrachloride have been measured with the TSS instrument at the Harwell Electron Linac. Data were taken at seven different scattering angles for a wavelength range of 0·2–3·5 Å. The observed diffraction patterns at high momentum transfer (> 8–30 Å-1) have been analysed in terms of the molecular form factor f 1(Q). It was found that the oscillation amplitudes could be satisfactorily described only by introducing an energy-dependent term into the Debye-Waller factors of the form factor. The f 1(Q) data were fitted with a four-parameter function for measurements at scattering angles of 150°, 90° and 58°. The carbon-chlorine bond length parameter was accurately defined in all cases and had a mean value of 1·766 ± 0·002 Å. The inclusion of an anharmonicity constant in the form factor gave an improved χ2-fit to the data with an increased value of 1·770 ± 0·002 Å for the bond length. The results are in excellent agreement with other measurements and show the importance of pulsed neutron techniques for molecular structure studies of disordered materials.