The Impact of Electron Beam Irradiation in Topaz Quality Enhancement

Most of the natural topaz is found as colorless. Variety attempt have been used to change its color. In this study, the process of enhancement by electron irradiation be carefully taken by consideration on the optimization of power and energy of electron, efficient cooling system, annealing process and radioactivity occurring and remaining. Electron irradiation was performed on topaz originated from Yen Bai province, in Vietnam. The two of topaz sample were irradiated by 20 MeV electron beam (e-beam) with different fluences of 1.34x10(16) cm(-2) and 2.64x10(16) cm(-2), respectively. The characteristic spectra obtained from the investigation compared to the natural topaz sample afterwards. Interaction of radiation with impurity ions in topaz sample during irradiation resulted in changing of colorless to sky blue topaz, which had the broad absorption band of UV-Vis spectroscopy at 620 nm. The ESR spectrum of topaz sample showing a single broad isotropic line with g = 2.012 that are correlated with an O-center in the topaz structure. FTIR spectra indicated that sky blue color may originate from the decomposition of hydroxyl group (OH) by the electron beam irradiation.