[en] Within this work we present comparative Brillouin and ultrasonic investigations of p-methoxybenzylidene p-(n-butylaniline), p-azoxyanisol, and 4-cyano-4’-pentyl-biphenyl performed in the vicinity of the nematic-isotropic transition. We confirm the existence of a universal hypersonic relaxation mechanism of weak activation energy and a related significant splitting of the two principal longitudinal acoustic modes within the nematic phase. Brillouin refractometry is proposed as a method to determine the magnitude of the nematic order parameter simultaneously with the second-order elastic stiffness constants. The origin of the hypersonic anisotropy is discussed in terms of thermal relaxations and the evolution of the nematic order parameter.
Disciplines :
Materials science & engineering Physics
Identifiers :
UNILU:UL-ARTICLE-2009-131
Author, co-author :
Grammes, C.
KRÜGER, Jan-Kristian ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Bohn, K.-P.
BALLER, Jörg ; University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Fischer, C.
Schorr, C.
Rogez, D.
Alnot, Patrick
Language :
English
Title :
Universal relaxation behavior of classical liquid crystals at hypersonic frequencies.
Publication date :
1995
Journal title :
Physical Review. E : Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
ISSN :
1063-651X
Publisher :
American Physical Society, College Park, United States - Maryland
