Anelastic processes in calix[n]arene-type organic molecules

We measured the anelastic spectrum of two organic molecules, calix[4]arene and p-tert-but-calix[4]arene. In both samples, a peak observed around 45-60 K for a measurement frequency of about 1 kHz was ascribed to the hopping of H atoms of the O-H groups, due to the close similarity of the physical parameters of these peaks with those obtained by a NMR relaxometry study. The present results reveal that anelastic spectroscopy is a good tool for studying atomic motion inside molecules at a mesoscopic level. (C) 2003 Elsevier B.V. All rights reserved

Hydrogen trapping by defects in semiconductors studied by anelastic spectroscopy

We review some results obtained by anelastic spectroscopy on H-related defects in III-V semiconductors. Anelastic measurements on InP lead to the formulation of a model explaining the conversion to the semi-insulating (SI) state. Moreover, in GaAs:Zn an extraordinarily fast relaxation rate has been measured and a possible explanation has been suggested. This results are reviewed and discussed in the light of new experiments on InP:Zn, whose spectrum shows a relaxation process similar to the one in GaAs:Zn. (C) 2003 Elsevier B.V. All rights reserved