Rotational Mobility in a Glassy Crystal Studied by Thermally Stimulated Depolarisation Currents (TSDC). An Experiment for the Physical Chemistry Laboratory

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 14 Issue 4 (2008) pp 175-179

Rotational Mobility in a Glassy Crystal Studied by Thermally Stimulated Depolarisation Currents (TSDC). An Experiment for the Physical Chemistry Laboratory

Joaquim J. Moura-Ramos*^,†, Natália T. Correia^‡, and Hermínio P. Diogo^§

^†CQFM – Centro de Química-Física Molecular and IN - Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal, mouraramos@ist.utl.pt, ^‡REQUIMTE, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and ^§Centro de Química Estrutural, Complexo I, IST, TULisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
Received June 20, 2008. Accepted September 2, 2009

Published online: 31 December 2009

Abstract. The present work shows how Thermally Stimulated Depolarisation Currents (TSDC) is a useful and powerful technique to study slow molecular mobility. At the same time, the pedagogic value of this experimental technique for undergraduate Physical Chemistry courses is underlined. A general introduction to the background of TSDC and to the treatment of the experimental results is provided, and the physical meaning of the information supplied is carefully discussed. The results of the TSDC study of the reorientational glass transition in the crystal pentachloronitrobenzene are presented as an illustration. We hope this will make clear the value of the technique for research and didactic uses.

Key Words: Laboratories and Demonstrations; physical chemistry

(*) Corresponding author. (E-mail: mouraramos@ist.utl.pt)

Article in PDF format (239 KB) HTML format

Supporting Materials:

Material for the instructor covering guidelines about the choice of experimental parameters, concepts of polarisation and depolarisation, molecular mobility and kinetics, detailed explanation of the physical background of the experimental technique and data treatment, preparation (424 KB)