Molecular dynamics in crystalline acetone studied by dielectric spectroscopy and neutron diffraction

Dielectric spectroscopy and neutron diffraction experiments in acetone have been performed in order to clarify the dynamical behavior and the structural changes associated to the unsolved thermal transition that takes place in the solid state around 130 K. The combination of dielectric experiments with neutron diffraction reveals the existence of a dielectric process in the stable crystalline phase of acetone. The evolution with temperature of the dielectric process, within the temperature range where the peak of the heat capacity was reported, supports that the transition is not of order-disorder type. The origin of the dielectric dispersion has been assigned to structural defects in the orthorhombic crystal phase of acetone.