A CEMS AND ABSORPTION MOSSBAUER-SPECTROSCOPY STUDY OF IRON ARACHIDATE LANGMUIR-BLODGETT-FILMS

Langmuir-Blodgett multilayers of ferric arachidate on silicon wafers have been investigated by means of conversion electron Mossbauer spectroscopy (CEMS) and absorption Mossbauer spectroscopy at different temperatures between room temperature and 4.2 K without and with an external magnetic field of 5 T. The Mossbauer spectra show Fe3+. A change of the relative line intensities in the measured spectra dependent on the observation direction is visible. It was found that the lines in the spectra are significantly broadened, which is due to a distribution of electric field gradients and isomer shifts. The reason for this is a slightly disordered iron environment. The quadrupole splitting is linearly correlated to the isomer shift. At low temperatures anti-ferromagnetic ordering has been observed and the orientations of the internal magnetic field and the electric field gradient in the crystal system have been determined. Due to its chemical structure this substance is an example of a quasi two dimensional system.