A determination of individual spectral densities in a smectic liquid crystal from angle dependent nuclear spin relaxation measurements

Deuterium relaxation experiments have been carried out at 38.4 MHz from 29.9 to 44.3°C on p-butoxybenzylidene-p-n-octylaniline (40.8), a smectic B liquid crystal, which had been deuterated in the aniline ring and along the octyl chain. The Jeener-Broekaert pulse sequence was used to determine the spectral densities of motion J(ω) and J₂(ω), and by rotating the sample such that the optic axis was oriented at three different angles to the external magnetic field we are able to obtain information about the frequency dependence not just of J₁ and J₂ but also of J₀. We report here the first measurements of the latter parameter at frequencies other than zero.