323,032 research outputs found
Ba2NaNb5O15 single crystals doped with Tm3+ and Ho3+: spectroscopy and energy transfer parameters
No full textSingle crystals of Ba2NaNb5O15 (BNN) activated with Ho3+ and Tm3+ have been grown by the 'flux growth' technique. The absorption spectra, the visible emission properties and the decay curves of the excited states have been measured at 10 and 298 K. The room temperature absorption spectra have been analysed by means of the Judd-Ofelt theory and the intensity parameters have been evaluated. The spontaneous transition probabilities, the branching ratios and the radiative lifetimes of the excited states have been calculated and compared with the experimental data in order to estimate the efficiency of the non-radiative processes. The connection between structural and spectroscopic properties has been pointed out in relation to the possible applications of these materials
Spectroscopy and energy transfer parameters of Tm3+ and Ho3+-doped Ba2NaNb5O15 single crystals
No full textSpectroscopic properties of Ho3+ and Tm3+ in Ca3Sc2Ge3O12 crystals
No full textSingle crystals of the Ca3Sc2Ge3O12 (CaSGG) garnet activated with Ho3+ and Tm3+ have been grown by the 'flux growth' technique. The absorption spectra, the visible emission properties and the decay curves of the excited states have been measured at 10 and 298 K. The room temperature absorption spectra have been analyzed in the framework of the Judd-Ofelt theory and the intensity parameters have been evaluated. The spontaneous transition probabilities, the branching ratios and the radiative lifetimes have been determined for the most important emitting states using the calculated intensity parameters, and the results have been compared with the experimental data in order to estimate the efficiency of the non-radiative processe
Spectroscopy and energy transfer parameters of Tm3+- and Ho3+-doped Ba2NaNb5O15 single crystals
No full textThe absorption and emission spectra of Tm3+- and Ho3+-doped Ba2NaNb5O15 crystals have been measured in the 1.5-2 mu m region. The lifetimes of the lowest excited states have been measured at 10 and at 298 K. The cross sections of the (Tm) F-3(4) H-3(6) and (Ho) I-5(7) I-5(8) transitions have been estimated and used to determine the (Tm) F-3(4) -> (Ho) I-5(7) energy transfer parameter. These results are discussed in order to evaluate the potentialities of this material as active medium in solid-state lasers operating at 2 Pm. (c) 2006 Elsevier B.V. All rights reserved
Optical spectra of Er3+ in Ba2NaNb5O15 single crystals
No full textThe absorption and luminescence spectra of Er3+-doped Ba2NaNb5O15 single crystals have been measured at 10 and 298 K. The lifetimes of the lower lying excited states, emitting in the visible and NIR regions, have been measured as a function of the temperature. From the oscillator strengths of the absorption transitions, the Judd-Ofelt intensity parameters have been evaluated. The spontaneous transition probabilities, the branching ratios and the radiative lifetimes have been determined for the most important emitting states using the calculated intensity parameters and the results have been compared with the experimental data. The stimulated emission cross section have been estimated for the 1.5 mu m transition. These experimental results are discussed in order to evaluate the potentialities of this material as active medium in solid state laser devices. (c) 2005 Elsevier B.V. All rights reserved
Study of the visible spectra of Ca3Sc2Ge3O12 garnet crystals doped Ce3+ and Pr3+
No full textWe have measured the absorption, the visible emission spectra and the lifetimes of Ca3Sc2Ge3O12 single crystals activated with Ce3+ or Pr3+. The crystals were grown by the ‘flux growth’ method. The optical spectra of the Ce3+-doped crystal consist of broadbands as a consequence of the strong electron–phonon coupling in the 2D(5d1) excited level, the emission band being located in the blue-green region with maximum at about 480 nm. The spectroscopic properties of CaSGG:Pr are affected by inhomogeneous broadening arising from the presence of non-equivalent optical centres. The spontaneous transition probabilities, the branching ratios and the radiative lifetimes have been calculated in the framework of the Judd–Ofelt Theory and compared with the experimental results for the 3P0 and 1D2 levels. The emission cross-sections of the transitions originating from the 3P0 level were calculated and compared with those reported for other Pr3+-doped crystals of technological interest
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
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