| Popis: |
The influence of high-energy (2 1MeV) electrons irradiation on spectroscopic properties of both undoped and chromium doped forsterite (Mg2Si04) crystals, as well as the corresponding extent of radiation-resistance of the crystals has been studied for the first time. It was found that such kind of irradiation results in formation of the induced additional absorption (AA) in both undoped and chromium-doped crystals, independently of crystal growth atmosphere. This AA is broad, structureless band in the range 300-1 100 nm with flat maximum at -450nm. Simultaneously the strong AA in UV part of spectrum appears. The shape of the band with maximum at 450 nm is practically the same for e-irradiated and previously studied y-irradiated forsterite crystals. It is also insensitive to Cr3+/Cr4+ ratio in crystals, as well as to additional codoping of crystals by Li+-ions. On the contrary to the shape, the intensity of the AA substantially depends on all above mentioned factors. Meanwhile, the irradiation had not led to change of the ratio of concentrations Cr4+:Cr3+:C2+. Thus, like in other oxide crystals observed induced absorption in the visible spectral range is caused, apparently, by point defects formation in the host. Possibly, these defects are hole 0 centers (ionized oxygen). The AA in UV belongs, apparently, to metal-to-ligand (oxygen ion) change transition.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
