Radiation effects in SiO2 under electronic excitation

Excitation of electrons in pure amorphous and crystalline bulk SiO2 may induce transient or stable modifications of their geometrical and electronic structure. Such situation is found either under electrons, X-rays, γ-rays, UV laser irradiation or along the path of very energetic ions (> MeV/amu). In turn, the bulk characteristics of the material such as loss tangent, Young's modulus can be changed. A review is given of this type of radiation effects. It includes surface studies, and bulk defect production. It has been adduced that defects production mechanism involves the self trapping of excitons. This process will be discussed in the frame of new results related to high local densities of electronic excitation. (orig.)