DTA and NQR studies of polymorphism in p-chlorofluorobenzene Original Research Article

Differential thermal analysis, and the 35Cl Nuclear Quadrupole Resonance frequency (νQ) and spin-lattice relaxation time (T1) were measured as a function of temperature in p-chlorofluorobenzene. Three different phases were found according to the thermal history of the sample and only one was stable up to the melting point. In one of the phases, the presence of molecular reorientations can be inferred from T1 data with activation energy of 3.7 kcal/mol. A value of 13.9 kJ/mol for the fusion heat of this compound has been obtained.