Relation between Ge(2) Center and 11.9 mT Hyperfine Structure of ESR Spectra in Ge-Doped Silica Fibers

The nature of the Ge(2) center and ESR hyperfine structure with a splitting of 11.9 mT, observed in germanium-doped silica fibers, is studied experimentally. It is considered that the Ge(2) center has a structure of –O–Ġe=O and that the 11.9 mT hyperfine structure is due to a structure of H–Ġe=O. The former is a precursor of the latter, i.e., the latter is yielded through chemical reaction of the former with hydrogen molecules.