Modelling of multifrequency ESR spectra of Fe3+ ions in crystalline and amorphous materials: A simplified approach to determine statistical distributions of spin-spin coupling parameters

Focussed on the understanding of the complex Fe3+ electron spin resonance ( ESA) spectra in crystalline and amorphous systems, the simulation program E SR-MAKRO-1 was developed, which allows the calculation of powder spectra of paramagnetic centers with 1/2 less than or equal to S less than or equal t o 7/2. For the reproduction of the ESR spectra of amorphous systems Gaussia n distributions of the zero-field-splitting parameters of second and fourth order (D, E, a, F) were implemented into the program. Applications of ESR- MAKRO-1 are given both for crystalline powders and for glassy systems. A st epwise analysis of the ESR spectra, allowing an approach to Fe3+ ESR spectr a of amorphous matrices and showing the influence of D, E, a, and F as well as their distributions, is given.