Abstract
Luminescence of Ti2+: LiF crystals in the wavelength range 650–900 nm excited using laser radiation is reported. The values of 10Dq and the Racah B parameter obtained from the present results indicate that in LiF the 1 E, 1 T 2, and 3 T 2 energy levels are almost at the “cross-over” point in the Tanabe-Sugano diagram. In consequence photoluminescence from all three energy levels to the ground state is observed. At low temperature (T ∼ 14 K) the emission is mainly due to sharp emission lines with weak vibronic structure due to the 1 E, 1 T 2→3 T 1 transitions of Ti2+ ions. The 3 T 2→3 T 1 broad-band emission is weak at low temperature, becoming stronger at 300 K due to a phonon-assisted tunnelling process, similar to that observed in Cr3+: garnets [1]. The excitation spectrum of these lines is a broad peak at 590 nm due to absorption in the 3 T 1→3 T 2 transition.
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References
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