Dynamics of amino GI-glycine molecule in triglycine sulphate by incoherent quasielastic neutron scattering

In the present work we present our experimental results concerning the molecular dynamics on a TGS polycrystalline sample, at different temperatures, using the Incoherent Quasi-Elastic Neutron Scattering - TOF method. The measurements were carried out above and below the critical temperature associated with ferroelectric-paraelectric phase transition, which characterize the TGS compound. The dynamics of GI-glycine molecule consists of two main motions: - The flip motion of the GI molecule from one side to another side of the mirror symmetry planes that are present at b=1/4 and b=3/4 in TGS unit cell; - The rotational motion of the amino group around C-N molecular axis during the flipping. By using the advantages provided by IQENS technique and applying the most suited models we have evaluated the characteristic times and energy levels of these molecular motion. (authors)