Analysis of evolution of electron-radiation-induced defects in white-luminescent, carbonized, mesoporous silica nanocomposite using transmission electron microscopy/cathodoluminescence

摘要

We examined the evolution of electron-radiation-induced defects in a white-luminescent, carbonized, mesoporous silica nanocomposite using cathodoluminescence (CL) and electron energy-loss spectroscopy associated with scanning transmission electron microscopy, in order to elucidate the microscopic origins of light emissions in the visible spectral range. The effects of electron irradiation on CL were analyzed based on the differential equations for kinetics of irradiation defects. The nanometric honeycomb silica framework was found to play essentially no role in the electron-excited light emission processes, in contrast to the case for photon-excited processes. The broad and continuous visible emission band in CL consisted of several luminescence components, that have been assigned to optically active point defects such as oxygen-deficient centers, and surface non-bridging oxygen hole centers (NBOHCs) in silica glass.