Noise-like magnetic resonance absorption in zeolites

Unusual X-band magnetic resonance spectra have been observed over the 77–500 K temperature range in polycrystalline specimens of zeolites treated to thermal oxidation. Narrow individual lines form a noise-like spectrum over the whole magnetic field scan range (up to 8000 G). However, the pattern differs from the real noise by strict reproducibility. A simple model is proposed to account for the phenomenon as the overlapping resonance lines of a large number of randomly oriented ferromagnetic microcrystal impurities.