Reinterpretation of the Fe-57 Mössbauer Effect of 1–1′-Diacetylferrocene in 4–4′-Bis(heptyloxy)azoxybenzene

Samples were prepared for Mössbauer analysis by incorporating 0.25–10% (by weight) of an iron bearing compound in the form of a ferrocene derivative in various tiquid crystals possessing both smectic and nematic phases. The samples were ordered in a 4–9 kg magnetic field in the nematic phase and cooled to the smectic phase for the Mössbauer experiments. Analysis of the resulting Mössbauer spectra showed that a non-zero effect was present only when the iron containing constituent occurred as a solid component. This conclusion was verified by X-ray diffraction studies of the samples. The systematic variation of both the percent effect and the ratio of the areas of the two quadrupole split peaks as a function of the angle between the aligning magnetic field and the gamma beam provided evidence that the solid crystals were small enough to be ordered by the smectic structure. The percent effect data were fit by assuming that the variation was due to the anisotropy of the liquid crystal lattice restorative forces and required knowledge of the planar orientation and the characteristic tilt angle of the smectic C. The dependence of the area ratio of the two quadrupole split peaks on the angle was found to be a function of the strength of the aligning field. This was explained qualitatively by assuming a direct dependence of the order parameter on the magnetic field.