Relaxation kinetics of metastable caffeine: a time resolved dielectric investigation

Anne-Amandine Decroix (1) , Laurent Carpentier (2) , Marc Descamps (2)

1 Physics
2 Physics

Using time resolved dielectric relaxation spectroscopy we have studied the kinetics of the first order phase transformation of caffeine from its high temperature rotational solid form to the room temperature phase. The results indicate that the kinetics can be fitted by a highly stretched exponential law. Kinetics thus differ from that of a “typical” nucleation and growth process. This unusual non-sigmoïdal evolution can be understood as being dominated by slow nucleation in grains with a dispersion of their size ranging below the characteristic dimension of the nucleation and growth process. The relaxation times of polarization are characterized by an activation energy closely correlated with that of the nucleation process.

Mots clés: Physical Sciences

Anne-Amandine Decroix, Laurent Carpentier, Marc Descamps. Relaxation kinetics of metastable caffeine: a time resolved dielectric investigation. Philosophical Magazine, 2008, 88 (33-35), pp.3925-3930. ⟨10.1080/14786430802585125⟩. ⟨hal-00513996⟩