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Electron paramagnetic resonance studies of slowly tumbling vanadyl spin probes in nematic liquid crystalsAn analysis of EPR line shapes by the method of Polnaszek, Bruno, and Freed is made for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals. The use of typical vanadyl complexes as spin probes for nematic liquid crystals is shown to simplify the theoretical analysis and the subsequent interpretation. Rotational correlation times tau and orientational ordering parameters S sub Z where slow tumbling effects are expected to be observed in vanadyl EPR spectra are indicated in a plot. Analysis of the inertial effects on the probe reorientation, which are induced by slowly fluctuating torque components of the local solvent structure, yield quantitative values for tau and S sub Z. The weakly ordered probe VOAA is in the slow tumbling region and displays these inertial effects throughout the nematic range of BEPC and Phase V. VOAA exhibits different reorientation behavior near the isotropic-nematic transition temperature than that displayed far below this transition temperature.
Document ID
19780024952
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Bruno, G. V. (Texas Univ. El Paso, TX, United States)
Harrington, J. K. (Texas Univ. El Paso, TX, United States)
Eastman, M. P. (Texas Univ. El Paso, TX, United States)
Date Acquired
September 3, 2013
Publication Date
January 1, 1978
Subject Category
Solid-State Physics
Report/Patent Number
NASA-CR-157609
Accession Number
78N32895
Funding Number(s)
CONTRACT_GRANT: NSG-1316
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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