Elastic and inelastic neutron scattering study of hydrogenated and deuterated trimethylammonium pillared vermiculite clays

Neutron scattering has been used to study the basal spacing and vibrational excitations of oriented samples of (CH3)3NH+ –vermiculite and its deuterated form (CD3)3ND+ –vermiculite. Both forms exhibit a basal spacing of 12.71 Å and a rich vibrational spectrum in the energy range 20–140 meV for Q perpendicular and parallel to the c-axis. These results are compared with infrared measurements and inelastic neutron scattering results of trimethylammonium halides over the same energy range. The torsional mode of the methyl group has been found to be split by ∼8 meV due to the top–top interaction between the methyl groups in the trimethylammonium vermiculite.