Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1237580 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2009 | 5 Pages |
Abstract
We present the results of photoluminescence (PL) measurements on 100 MeV Ni8+ ion irradiated Al2O3 single crystals in the fluence range 1 Ã 1011 to 5 Ã 1012 ions/cm2. A sharp PL peaks at â¼693, 695, 707 and 730 nm are recorded with an excitation of 442 nm He-Cd laser beam. The sharp emission peaks at 693 and 695 nm are attributed to R2 and R1 lines of Cr3+ ions, and they are related to the transition from 2Eg â 4A2g. The weaker sharp peaks called N lines appear at â¼707 nm and its origin is ascribed due to closely coupled pairs of Cr3+ ions. The longer wavelength part of the PL spectra at â¼730 nm may be due to increase of groups of more than two Cr3+ ions. It is observed that the broad emission band (450-650 nm) consists of four bands centered at 470, 518, 547 and 618 nm, respectively. The 470, 518 and 547 nm bands are corresponding to F2+, F2 and F22+ defect center, respectively. It is observed that the PL intensity of F2, F22+, R and N lines increases with Ni8+ ion fluence. This can be attributed to increase in concentration of color centers responsible for luminescence through radiative recombination.
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Authors
H. Nagabhushana, B. Umesh, B.M. Nagabhushana, B.N. Lakshminarasappa, Fouran Singh, R.P.S. Chakradhar,