Nanostructures and Nanocrystals with Radiation Induced Color Centers: Optical Properties and Applications

Optical properties and some applications of radiation-induced point defects (color centers) in dielectric nanocrystals and thin films are presented. The recent developments of novel high-spatial resolution X-ray imaging detectors based on the photoluminescence of optically active defects in lithium fluoride thin films are described. Opportunities to locally change and control the material optical properties at sub-micron scale through the formation of electronic point defects are discussed. Comparison between the optical response of radiation-induced defects in bulk crystal and in thin films is highlighted. It is shown that in nanocrystals and in the near-surface layers of lithium fluoride crystals, some color centers possess optical properties different from those of the defects in bulk crystal. Photoluminescence and photoluminescence excitation spectra and Huang-Rhys parameters are presented for radiation-induced defects in lithium fluoride nanocrystals. Some dosimetric characteristics of nanocrystals and crystals (microcrystals) of the same composition for doped insulating materials are compared.