​Optical characteristics of sapphire crystal (4)

Optical characteristics of sapphire crystal (4)

The TSL spectra of sapphire irradiated by neutrons and excited by X-rays include bands located at 2.4, 3.7 and 2.8-3.1 eV, which are consistent with the luminescence bands of photoexcitation. The luminescence bands located at 260, 330, 410 and 510 nm after proton irradiation have been recorded [58]. Several luminescence (emission) bands (3.80, 3.18, 2.82, 2.43, 2.23 eV) appear in the excitation of neutron-irradiated sapphire, regardless of the prior history of the three samples [59].

In addition to luminescence in thermal equilibrium with the lattice, non-equilibrium luminescence or emission based on electron-to-electron and electron vibrational levels has also been observed in Cr:Al2O3 laser intense pumping. This luminescence possesses a continuous spectrum, and its intensity Depending on the wavelength of the excitation laser, the intensity is several orders of magnitude weaker than equilibrium luminescence.

Luminescence due to crystal defects grown under thermodynamically nonequilibrium conditions is often observed in different regions of the spectrum. The 330 nm band is caused by the main transition IB→IA located in the center of F+. The emission in the 450-460 nm region is related to R center-related (three unified F centers, for example, three anion vacancies that capture three electrons) [60]. The luminescent liquid in the 420 nm region is related to the aggregation center. According to the reported data[60] 60], which is a P-center (adjacent anion and cation vacancies). The capture of an electron by this pair results in the formation of a P-center, while the capture of a hole results in a P2-center. Appear. 

Emission in the 510 nm band was observed in the neutron irradiated sample, which was attributed to the interstitial Al+[62]. This ion can be stabilized by electron capture. This has been based on the absorption band at 4.1 eV, the absorption band at 2.45 eV Luminescence and a narrow luminescence band at 3.8 eV confirmed. Figure 2.47 shows a schematic diagram of its energy level proposal.

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