Excited State Of Ce3 Research Articles

Effect of Ce codoping on the thermoluminescence dosimetry and photoluminescence behavior of SrBPO5:Dy/Sm/Eu

Effect of Ce on the thermoluminescence and photoluminescence of Dy, Sm and Eu in SrBPO5 was investigated. Samples of Sm, Dy, Eu doped and Ce-Dy/Sm/Eu codoped SrBPO5 were prepared through the high temperature solid-state synthesis route. Prepared phosphor samples were checked for their phase purity with powder X-ray diffraction analysis. Thermoluminescence glow curves were recorded for the phosphors and explored for the dosimetric applications. TL glow curves of 20 Gy gamma irradiated SBP:Dy0.01−1/Sm0.01−1/Eu0.01−1 and SBP:Ce1-Dy0.01−1/Sm0.01-Eu0.01−1 were obtained with 2 K/s heating rate. Gamma dose response of the phosphor samples were studied from 5 mGy to 100 Gy. The SBP:Ce1-Dy0.5 and SBP:Ce1-Sm1 demonstrated excellent dose linearity to gamma dose. The thermoluminescence behavior indicated that, Ce codoping has profound effect on the amount and type of traps and the glow peak intensity of Ce codoped SBP:Dy/Sm enhanced significantly. The photoluminescence study suggested efficient exchange type energy transfer interaction between excited states of Ce3+ and Dy3+/Sm3+ in the SrBPO5 host. The results confirmed the suitability of SBP:Ce-Dy/Sm phosphors for the thermoluminescence applications. The range of dose linearity of SBP:Ce-Dy, and SBP:Ce-Sm phosphor were found to be better than the commercial CaSO4:Dy and could be promising materials for personal as well as accidental dosimetry.

Crystal Growth and Scintillation Properties of Ce-Doped ${\rm K}_{2}{\rm NaLuF}_{6}$

Ce 0.1, 0.5, 1.0, and 2.0 mol%-doped K2NaLuF6 crystals with 2 mm in diameter and 30-50 mm in length were grown by micro-pulling-down method. The photoluminescence spectra under ultraviolet excitation showed intense emission ascribed to 5d-4f transitions of Ce3+ replacing Lu3+ isolated octahedral site. In the radioluminescenced spectra under alpha-ray irradiation, the emission band is due to the transition from the lowest 5d excited state of Ce3+ to 2F5/2 ground state level is dominant. The light yields of Ce:K2NaLuF6 under 5.5-MeV alpha-ray excitation was estimated to be approximately 1.2 to 1.8% of those of BGO.

Electronic transport in thin film electroluminescence of SrS:Ce

Thin film electroluminescent (TFEL) devices based on the scheme of SiO2/SrS:Ce/SiO2/SiO were fabricated, and blue–green emission was observed in the devices. The electronic transport process is strongly affected by the mixing interaction between the conduction band of SrS and the excited state of Ce3+. The photoluminescent excitation and the wave forms of time-dependent electroluminescent emission show that recombinant luminescence is the main process in SrS:Ce TFEL. The experimental results reveal that the excitation mechanism is related to the sulfur vacancies.

Energy transfer and sensitised luminescence in single crystals of CaF2:(Ce+Mn) system

The measurement of absorption, luminescence, and relative intensity of cerium and manganese emission during fluorescence, on single crystals of CaF2:(Ce+Mn), have been reported in this paper. The occurence of the absorption bands have been explained in the following manner: (i) 250 mu band due to the transfer transition from F− to2D, the excited state of Ce3+, (ii) 305 mμ band due to the characteristic transition of Ce3+ and (iii) 335 mμ band due to the perturbed level of the lattice. The emission bands have been explained like this, (i) 320 and 340 mμ bands due to the transitions of2D to2F5/2,7/2 levels of Ce3+ (ii) 380 and 440 mμ bands corresponding to the perturbed levels and (iii) 520 mμ band due to transfer of energy from cerium centres to manganese centres. The results of the present investigation indicate that energy transfer in this system occures not only from cerium to manganese centres but also from cerium to cerium and cerium to perturbed levels of the lattice. It has also been observed that energy transfer process is temperature dependent in this case. An energy level scheme is proposed to explain the transfer mechanism.