Structural changes induced in silica by ion irradiation observed by IR reflectance spectroscopy.

The structural changes produced by ion irradiation, He + (2.5 MeV), O 4+ (13.5 MeV), Si 4+ (24.4 MeV), and Cu 7+ (32.6 MeV), in different types of silica (KU1, KS-4V and Infrasil 301) were observed by IR reflection spectroscopy. The IR reflectance spectra were measured between 400 and 1400 cm −1 . Structural bands wavenumber of the three silica grades, irradiated with the same ion and fluence, is independent on OH or impurity content of silica. Modification in the surface structure of the irradiated face of a silica sample was studied monitoring the changes in the wavenumber of fundamental structural bands as function of the ion fluence. Samples irradiated at high ion fluence present a shift of known structural bands and new IR reflection bands around 608 cm −1 and between 920 and 990 cm −1 , corresponding to a new structure. The spectra of neutron irradiated samples at fluences 10 17 and 10 18 n/cm 2 were also measured and compared with ion irradiated samples. [ABSTRACT FROM AUTHOR]