Ry. Dong et Xd. Shen, DYNAMICS OF A LIQUID-CRYSTAL BY DEUTERIUM NMR - THE ANALYSIS OF DIRECTOR FLUCTUATIONS AND REORIENTATION OF MOLECULES, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 101(26), 1997, pp. 4673-4678
The zero-frequency spectral densities J(0)(0) data(1) for the liquid c
rystal p-(methoxybenzylidine)-p-n-butylaniline (MBBA) is quantitativel
y interpreted using a model that includes director fluctuations and ro
tational diffusion of symmetric rotors in a nematic phase. The contrib
ution to J(0)(0) from director fluctuations has mainly a second-order
component, whereas the first-order contribution to J(1)(omega) is supp
ressed in the megahertz region (Larmor frequencies are 15.3 and 46 MHz
) due to the high-frequency cutoff, which is estimated to be around 3-
10 MHz for MBBA. A global target approach is used in the analysis of a
ll the available spectral densities. As a result, motional parameters
and a molecular prefactor for director fluctuations are obtained in th
e nematic phase of MBBA.