Temperature-dependent crystal structure analysis of methyl iodide by high-resolution neutron powder spectroscopy

High resolution neutron powder diffraction data recorded at 4.5 K confirm the orthorhombic structure of methyl iodide reported previously by Kawaguchi et al. (1973) from an X-ray single-crystal study at 193 K. The present study, using neutron powder diffraction, provides more precise structural parameters and reliable atomic coordinates for the hydrogen atoms enabling the methyl group libration to be analysed as a function of temperature up to 193 K