Proton-spin thermometry at low fields in liquid crystals

摘要: The relaxation rate, resulting from the order-director fluctuation, of dipolar energy benzene proton-spin pairs in a liquid crystal was calculated. For this mechanism ratio $\frac{{T}_{1}}{{T}_{1D}}$ is 3. Proton-spin-lattice times, ${T}_{1}$, ${T}_{1X}$, and ${T}_{1D}$, as well transverse longitudinal magnetization, were measured crystals para-octyloxybenzoic acid para-azoxyanisole (PAA). Since spins on one liquid-crystal molecule are isolated other molecules, each represents an independent small ensemble. Although macroscopic thermodynamics applies to large sample these ensembles, spin-temperature concept should only be applied such systems with care. In both crystals, spin-relaxation processes analyzed using spin temperature. It shown that PAA Zeeman rotating frame influenced by proton-to-nitrogen relaxation.