Cold Neutron Scattering at CH3‐, CH2‐ and OH‐Protons in Methanol and Ethanol

Abstract

AbstractTotal cross sections of CH3OH, CH3OD, CH2DOH, CHD2OH, CD3OH, and CH3CH2OH, CH3CH2OD, CH3CD2OH, CD3CH2OH have been measured with cold neutrons between 5 Å and 15 Å. The slopes S of the scattering cross section per proton vs the neutron wavelength indicate the different microdynamic behaviour of the individual protons inside the molecule. In methanol S = 3.4 ± 0.8 barn/Å for an OH‐proton and S = 12.1 ± 0.5 barn/Å for a CH3‐proton is explained by a relatively free internal CH3 rotation and a hindered motion of the OH‐proton. In ethanol the OH‐proton with 1.3 ± 0.8 barn/Å seems to be much more hindered than in methanol, whereas a CH3‐proton with S = 9.8 ± 0.4 barn/Å behaves quite similar to a CH2‐proton with 9.1 ± 0.5 barn/Å.