Assessment of the recoilless fraction of fine goethite particles in Mossbauer spectroscopy

Abstract

The relative recoilless fractions of goethite samples as a function of particle size were successfully determined without using the Debye approximation. The data showed that the absolute recoil-free fraction of goethite reduced with decreasing the particle size. The reduction in particle size became a cause of the particle motion that was possibly induced by a momentum transfer from incident gamma-quanta to the goethite particles. Also, the reduction in the particle size somewhat increased the vibration frequency of the particle motion. When small goethite particles were embedded in a binder matrix, their absolute recoil-free fraction increased with decreasing the vibration frequency. It appears that the different properties of the binding material are possibly related to the vibration frequency of the particle motion.