Nagabhushana H, Umesh B, Nagabhushana B M, Lakshminarasappa B N, Singh Fouran, Chakradhar R P S
Department of PG Studies in Physics, Govt. Science College, Tumkur 572 103, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2009 Aug 15;73(4):637-41. doi: 10.1016/j.saa.2009.03.005. Epub 2009 Mar 26.
We present the results of photoluminescence (PL) measurements on 100 MeV Ni(8+) ion irradiated Al(2)O(3) single crystals in the fluence range 1x10(11) to 5x10(12) ions/cm(2). A sharp PL peaks at approximately 693, 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 R(2) and R(1) lines of Cr(3+) ions, and they are related to the transition from (2)E(g)-->(4)A(2g). The weaker sharp peaks called N lines appear at approximately 707 nm and its origin is ascribed due to closely coupled pairs of Cr(3+) ions. The longer wavelength part of the PL spectra at approximately 730 nm may be due to increase of groups of more than two Cr(3+) 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 F(2)(+), F(2) and F(2)(2+) defect center, respectively. It is observed that the PL intensity of F(2), F(2)(2+), R and N lines increases with Ni(8+) ion fluence. This can be attributed to increase in concentration of color centers responsible for luminescence through radiative recombination.
我们展示了对能量为100 MeV的Ni(8+)离子辐照的Al₂O₃单晶进行光致发光（PL）测量的结果，辐照通量范围为1×10¹¹至5×10¹²离子/cm²。用442 nm的氦镉激光束激发时，记录到在约693、695、707和730 nm处有尖锐的PL峰。693和695 nm处的尖锐发射峰归因于Cr(3+)离子的R₂和R₁线，它们与从(²Eg)→(⁴A₂g)的跃迁有关。在约707 nm处出现的较弱尖锐峰称为N线，其起源归因于Cr(3+)离子的紧密耦合对。PL光谱约730 nm处的较长波长部分可能归因于两个以上Cr(3+)离子基团的增加。观察到宽发射带（450 - 650 nm）分别由四个以470、518、547和618 nm为中心的带组成。470、518和547 nm的带分别对应于F₂⁺、F₂和F₂²⁺缺陷中心。观察到F₂、F₂²⁺、R和N线的PL强度随Ni(8+)离子通量增加。这可归因于通过辐射复合产生发光的色心浓度增加。
