Fourier transform (FT) - EPR spectroscopy on neutron irradiated silica fiber tubes

The electron spin echo spectra of neutron irradiated silica fiber tubes were recorded at 2 and 9.5 GHz. Three signals were detected in these samples attributed to the E'1-center, E'1-center interacting with hydrogen atom, and 29Si-E'1-center. The relaxation times T1 and T2 for these defects were determined at 2 and 9.5 GHz. The T2 was independent of the temperature down to 110 K and then increased with the decrease of the temperature of measurements. The T1 relaxation time of the 28Si and 29Si E' center were the same within the errors of measurements down to 35 K and followed the same dependence on T. The T1 vs. T curves were simulated using a superposition of three different relaxation mechanisms. A Fourier Transform EPR spectrum was derived from the ESEEM pattern. The ESEEM pattern was simulated in order to extract the structure of the E' center