Three broad cathodoluminescence bands centered at ~2.02eV (red), ~2.78eV (blue), and ~3.45eV (ultraviolet) were emitted from silica nanowires synthesized by thermal evaporation at high temperature. The luminescence intensities of both the red and ultraviolet bands decreased upon electron-beam irradiation, while the intensity of the blue band increased with both irradiation time and specimen temperature. The red, blue, and ultraviolet bands were identified as being radiative transitions involving: non-bridging O hole centers, O-deficient centers, and the peroxy linkage. The varying time- and temperature-dependent luminescence intensities could be explained by the mutual transformation of these defects, which was driven by the irradiation- and heat-induced migration and desorption of radiolytic O.

Luminescence Centres in Silica Nanowires. N.G.Shang, U.Vetter, I.Gerhards, H.Hofsäss, C.Ronning, M.Seibt: Nanotechnology, 2006, 17, 3215-8