In situ luminescence qualification of radiation damage in aluminas: F-aggregation and Al colloids

In-situ luminescence monitoring of ion-induced damage evolution in SiO2 and Al2O3

“…Note that the saturation kinetics of the F 2 þ band is correlated with the buildup and decay kinetics of the F band. Similar evolution behavior of the F, F þ , and F 2 þ centers at low ion fluence has also been reported by Malo et al [14]. The ratio between the intensity (as calculated by the Y F þ /Y F area ratio) of the F þ and F bands (not shown) exhibits exponential growth in the low fluence stage, but at about 1 Â 10 15 cm À 2 it saturates at a value of 45.…”

“…This latter process has been confirmed by both the IBIL ( Fig. 9(a)) and optical absorption spectra [14]. The formation of every F 2 þ center removes two F/F þ centers, and could account for some of the reduction in the signal from single vacancy centers.…”

“…Instead a steady state is reached. According to Malo et al [14] the F 2 þ center is an essential precursor to higher oxygen vacancy aggregates (F 3 , F 4 , etc.) and is a well-known nucleation site for aluminum colloids.…”

“…Luminescence provides information about the upper electronic levels of a material (near the Fermi level), particularly for intra-gap levels associated with impurities and defect centers, such as those introduced by irradiation. The luminescence induced by ion-beam irradiation, commonly named ionoluminescence or ion beam-induced luminescence (IBIL), is a technique capable of acquiring information about intrinsic or pre-existing defects in materials as well as in-situ information about the microscopic processes accompanying the generation of damage from energetic ions, their kinetic evolution with the accumulation with increasing ion fluence, the formation of color centers, and their recovery with thermal annealing [2][3][4][5][6][7][8][9][10][11][12][13][14]. The visible light produced during luminescence is a result of outer shell transitions.…”

“…In several of these applications, both materials are subject to high fluxes of ionizing radiation such as photons in laser technology, or neutrons and charged particles in spacecraft, accelerators and nuclear fission and fusion facilities [19,20]. The use of the radiation induced light emission, such as IBIL, as a remote method to monitor material modification would be of great interest in fusion devices as it may permit in-situ monitoring of material performance [13,14]. Therefore, significant effort has been devoted to understanding the effects of ion irradiation on the atomic and electronic structures of crystalline and amorphous SiO 2 .…”