Irradiation effects on the OH-related infrared absorption band in synthetic wet silica

The effects of β-irradiation on the OH-related infrared (IR) absorption band in synthetic wet silica samples have been investigated by Fourier transform infrared spectroscopy. Depending on the accumulated doses, β-irradiation affects different zones of the IR composite band at about 3670 cm−1, assigned to the OH stretching modes of silanol groups. These modifications are independent of the original OH content. The results are discussed considering possible radiation-induced changes of the silanol bonding configuration and of the glass network. These are monitored by revealing the IR band a 2260 cm−1, which is related to the distribution of Si–O–Si bond angle. We have identified the existence of two regimes as a function of radiation dose; low radiation doses produce the reduction of the Si-OH hydrogen-bonded states in favor of the isolated ones, while the opposite effect is observed at higher doses, where the formation of H-bonded pairs seems to be favored.