ANOMALOUS SPIN-LATTICE RELAXATION IN THE NEMATIC PHASE OF THERMOTROPIC LIQUID CRYSTALS

R. H. ACOSTA; D. J. PUSIOL

Caxambu, Brasil

Congreso; XXIII Encontro Nacional de Fisica da Materia Condensada; 2000

Experimental T1-profiles of Propylcyano- phenylcyclohexane (3-PCH) at different temperatures (Figure1) were recorded by means of a conventional  (5*106<nL<108Hz) and fast field cycling (103<nL<106 Hz) NMR spectrometers. With both instruments the random error of the individual T1 points is less than 10% after appropriate signal averaging, and the sample temperature has been controlled with an accuracy of at least 0.2oC. The FFC experimental set-up is home made [7], the design is based on a electronically switched FFC-NMR spectrometer which uses a special air core magnet design and a MOSFETs magnet control and power switching [8]. Additional coils are used for shimming the detection magnetic field. The earth’s field is compensated by an external pair of dc driven Helmholtz coils.