Energy level of Ce3+ at energy higher than 2000 cm-1 in silica

Description

Among rare-earth ions, cerium is widely used in laser technology, fast scintillators and white emitting LEDs thanks to its ability to emit in the UV-visible. This emission band is due to the transition of an electron from the 5d energy levels to the 4f ones. As a consequence, the position of its emission wavelength depends strongly on the environment. It spans from UV in fluoride to red in nitride. Electrons on the two 4f levels (2 F 5/2 and 2 F 7/2) are shielded from the external field by the 5s 2 and 5p 6 electrons. Then, the two 4f levels are usually known to be separated by ~2000 cm-1 whatever the change of the environment. However, it has been reported recently that a higher 4f energy level does exist in crystals, located at 3639 cm-1 in Gd 3 Ga 5 O 12 [1] and ~4000 cm-1 in Lu 3 Al 5 O 12 [2]. In cerium-doped silica glasses prepared by sol-gel, we have measured absorption spectra in the 4f energy levels domain. An absorption band at ~5300 cm-1 has been observed. During this presentation, we shall discuss on the origin of this absorption band, based on results obtained both in silica and silicates (silica containing aluminum or sodium) glasses prepared by sol-gel, melt-quenching and phase vapor (MCVD process).

Abstract

International audience

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