Studies of behavior of hydrogen in fused silica by ion beam analysis technique

Retention and thermal release behavior of hydrogen isotopes in fused silica, synthesized silica and optical fibers were investigated by ion beam analysis technique. Initially contained H in the interior of the specimens is about 0.1∼0.2 at.% at room temperature, irrespective of the nominal value of OH concentration. Besides, H atoms more than 1 × 10¹⁶H/cm² was found at the surface. The thermal release of the H atoms from the interior was affected by retrapping at the near surface. During 5 keV ion injection, the retained D in the implanted layer was quickly saturated with a concentration of about 1 × 10²¹D/cm³. Under the subsequent D injection to doses above 1 × 10¹⁸D/cm², D atoms were trapped with a concentration about 1 at.% in the depth far beyond the projected ranges of D ions. Thermal release of D in the injected layer started at lower temperature than that from the larger depth for lower implantation dose, while the two release curves close to each other for the higher dose. Irradiation of 10 keV He ion into the fused silica caused H up-take in the He implanted depth, where no He atoms were retained.