Abstract
Using the temperature and frequency dependences of proton relaxation rates in -methoxybenzylidene butylaniline (MBBA), measured in the temperature range of 316.2-350 K and the frequency range of 4-20 MHz, we confirm the necessity of considering critical fluctuations (CF) in two parts—"local" and "nonlocal" as envisaged in a recent theoretical study—characterized by their corresponding correlation times and . Both and have also been determined at different temperatures. In such determinations, use has been made of the critical index for , the same as observed in light scattering experiments, and our is in reasonable agreement with these results. Like , also shows critical behavior but with a slightly higher index. The magnitude of is also appreciably larger than at the same temperature. These observed differences between and , and the behavior of nuclear relaxation rate at predicted by the Landau-de Gennes theory suggest strongly a close similarity between the nematic-isotropic (NI) transition and the Bose-Einstein condensation; is the apparent critical temperature if the IN transition were continuous.
- Received 7 September 1977
DOI:https://doi.org/10.1103/PhysRevB.21.1194
©1980 American Physical Society