Numéro
J. Phys. IV France
Volume 03, Numéro C4, Septembre 1993
4th International Workshop on Positron and Positronium Chemistry
Page(s) C4-311 - C4-316
DOI http://dx.doi.org/10.1051/jp4:1993450
4th International Workshop on Positron and Positronium Chemistry

J. Phys. IV France 03 (1993) C4-311-C4-316

DOI: 10.1051/jp4:1993450

Supercooling studies in n-p-cyano-p-heptyl biphenyl using positron, lifetime spectroscopy

K. CHANDRAMANI SINGH and P.C. JAIN

Department of Physics & Astrophysics, University of Delhi, Delhi 110 007, India


Abstract
Supercooling studies have been performed in n-p-cyano-p-heptyl biphenyl using positron lifetime spectroscopy. Positron lifetime measurements have been performed during the heating cycle of samples prepared by either quenching or slow cooling from the nematic phase. The behaviour of these two samples is found to be different. In case of the quenched sample, the material seems to have transformed into a glassy solid. The o-Ps pick-off lifetime in the quenched sample exhibits a strong temperature dependence. Its value exhibits six broad peaks at 176, 195, 214, 233, 248 and 257K. These temperatures have been ascribed to various molecular motions. The sample exhibits a glass transition at about 268K.



© EDP Sciences 1993