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Title: Excitation and emission spectra of anti-Stokes luminescence of Tm3+ in glass ceramics doped with various concentrations of sensitizer
Authors: Kathuria, R
Chandra, B P
Ramrakhiani, M
Bisen, D P
Keywords: Anti-Stokes luminescence;Rare-earth doped glass ceramic;Excitation and emission spectra;Luminescence of Tm3+
Issue Date: Feb-2004
Publisher: NISCAIR-CSIR, India
IPC Code: C09 11/07
Abstract: In certain rare-earth doped glass ceramics luminescence emission has been observed at wavelength shorter than the exciting wavelength. This is known as anti-Stokes luminescence or up-conversion, which is due to accumulation of excitation energy by rare-earth ions. In Tm3+ and Yb3+ doped glass ceramics, Tm3+ acts as an activator and Yb3+ acts as a sensitizer. The activator concentration was kept constant at 0.2 mol% and the sensitizer Yb3+ concentration was varied from 0.0 mol% to 20 mol%. In emission spectra of glass ceramics doped with Tm3+ and Yb3+, under infrared excitation (966 nm) one peak of high intensity was found at different wavelengths between 400 to 500 nm for different concentrations of sensitizer. The peak is slightly shifted towards shorter wavelength with increasing concentrations of the sensitizer. This reveals that 3-photon up-conversion is prominent and presence of Yb3+ ions slightly shifts the energy levels of Tm3+. In the excitation spectra of glass ceramics doped with Yb3+ and Tm3+ , initially the emission intensity increases with increasing wavelength, attains an optimum value for 920 nm, 930 nm, 950 nm and 960 nm and then it decreases with further increase in the wavelength. These photon energies may correspond to energy difference between levels of Tm3+ or Yb3+. Both in the excitation spectra and emission spectra, initially the anti-Stokes luminescence intensity increases with sensitizer concentration, attains an optimum value and then it decreases with further increase in the sensitizer concentration.
Page(s): 136-141
ISSN: 0975-1041 (Online); 0019-5596 (Print)
Appears in Collections:IJPAP Vol.42(02) [February 2004]

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