Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: POSTERS Dynamics and Diffusion
CPP 8.11: Poster
Montag, 25. Februar 2008, 16:45–19:00, Poster A
On the acoustic director interaction in the smectic A phase — •Josefina Perlo1, Luis Aguirre1, Jorge Revelli2, and Esteban Anoardo1 — 1Universidad Nacional de Cordoba (FaMAF), Cordoba, Argentina — 2Instituto de Fisica de Cantabria, Santander, Spain
It was shown that an acoustic field can be coupled to the collective dynamics of nematic and smectic-A specimens. Effects of ultrasound on the collective dynamics (order director fluctuations ODF) were observed through the study of the Larmour frequency dispersion of the spin-lattice nuclear magnetic relaxation time.
A fundamental task for the interpretation of the results was the understanding of the interaction mechanism between the acoustic field (a wave vector) and the mesophase director. First works on nematic showed that the acoustic field has an orienting action on the nematic director field.
The idea was extended to the smectic-A phase. The smectic nature of the problem was firstly simplified by considering a nematic in the limit of large anisotropy in the elastic constants. In this limit, the predicted behavior of the relaxation dispersion under sonication showed to be inconsistent. An improved result was obtained by considering the coupling between the smectic order and the ODF.
In this work we investigate details of the interaction between acoustic field and smectic-A phase through the inclusion of elemental features of this phase. We show that the acoustic director interaction can be enhanced if the external acoustic field matches an eigenmode of the smectic system.