Papers by Keyword: Energy Transfer

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Authors: Xin Mu Zhou, Yong Xiu Li
Abstract: Cd1-xZnxSiO3:0.01 Mn2+ phosphor was synthesized by sol-gel method. It was characterized by excitation, emission spectra and XRD. The luminescent properties show the phenomenon of energy transfer from the tetrahedral coordinated Mn2+ ion to the octahedral coordinated Mn2+ ion after exciting by ultraviolet light, which boost the performance of the phosphor. With the increasing of Zn2+ in Cd1-xZnxSiO3:0.01 Mn2+ phosphor, it was observed the excitation spectra broadened and a red shift in the emission spectra, which emission peak moved from 580nm to 589nm.
Authors: Yu Jie Chen, Feng Lan Han, Zhao Luo
Abstract: Na2BaMgP2O8 phosphors were synthesized by a standard solid state reaction and their luminescent properties were investigated. The phase structure was analyzed by X-ray powder diffraction measurement. Under the excitation of 365nm, Na2BaMgP2O8:Tb3+, Eu3+ phosphors show two color bands of green and red color due to 5D47F5 transition of Tb3+ ions and 5D07F2 transition of Eu3+ ions, respectively. The emission intensity of Tb3+ deceased with the increasing concentration of Eu3+, which verified that an effective energy transfer occurred from Tb3+ to Eu3+ in Na2BaMgP2O8 host. The present study indicated that the phosphors have a high potential application in solid state lighting.
Authors: Elena F. Polisadova, Vitaly A. Vaganov, Damir T. Valiev, Habibula A. Abdullin, A.A. Marhabaeva, D.D. Kerimbaev
Abstract: The results of the study of spectral and decay kinetic characteristics of the pulse cathodoluminescence (PCL) for the group of industrial “white” LEDs phosphors with different composition of the host and dopants are presented. The quantitative characteristics of the PCL: position and half-width of the luminescence spectra, the luminescence decay times were determined.
Authors: Wu Lei Zhou, Tuo Cai, Jian Xiao, Xue Ting Han, Jian Bo Liu, Liang Xu, Jian Guang Chi, Shao Hong Gao, Xi Ping Cai, Li Min An
Abstract: CdSe semiconductor nano crystals (NCs) and Polyaniline (PAni) are mixed uniformly to prepare CdSe NCs/PAni complex. PAni can quench the fluorescent signal of CdSe NCs. The fluorescent intensity of CdSe NCs/PAni complex is related to the size of CdSe NCs and concentration of PAni. Ultraviolet visual (UV-Vis) absorption spectra and fluorescence spectra are employed to analysis the quenching phenomenon. The mechanism of fluorescence quench is dependent on two factors: on one hand, the FÖrster resonance energy transfer conducts from CdSe to PAni; on the other hand, PAni can intercept the electron charge of CdSe and lead to the interruption of radiative recombination.
Authors: Elisabetta Collini
Abstract: One of the most surprising and significant advances in the study of the photosynthetic light-harvesting process is the discovery that the electronic energy transfer (ET) might involve long-lived electronic coherences, also at physiologically relevant conditions. This means that the transfer of energy among different chromophores does not follow the expected classical incoherent hopping mechanism, but that quantum-mechanical laws can steer the migration of energy. The implications of such quantum transport regime, although currently under debate, might have a tremendous impact in our way to think about natural and artificial light-harvesting and suggest new directions for the development of artificial devices for the efficient capture and re-use of solar energy. Central to these discoveries has been the development of new ultrafast spectroscopic techniques, in particular two-dimensional electronic spectroscopy, which is now the primary tool to obtain clear and definitive experimental proof of such effects.
Authors: Ce Zhao, Ke Hui Qiu, Xia He, Guo Yin Yan, Si Zhu Chen
Abstract: A series of red-emitting phosphors, Eu3+-doped and Eu3+ with Sm3+ co-doped Li2CaSiO4, were prepared by the combustion method. The phase composition was investigated by XRD, and photoluminescent properties were characterized by fluorescent spectrophotometer. The results show that the diffraction peaks of samples all match well with that of Li2CaSiO4 [JCPDS NO. 27-0290]. The excitation spectra consists of the broadband and the sharp lines, which are assigned to the charge transfer band (CTB) of Eu3+→O2– and the typical intra-4f transitions of the Eu3+ ions, respectively. The emission spectrum covers the characteristic f-f transitions of Eu3+, namely, 5D07F1 (596 nm), 5D07F2 (620 nm), 5D07F3 (657 nm) and 5D07F4 (705 nm). The concentration quenching occurs when Eu3+ mol fraction equals to 9%. When Eu3+and Sm3+ were co-doped, the luminous intensity of the emission spectrum was superior to the Eu3+ mono-doped, which explains the Sm3+ has a sensitization effect for Eu3+.
Authors: Hui Jiang Liang, Yu Zeng, Kang Ping Xu, Zhi Wei He, Ming Yu Gao
Abstract: The batteries in a battery pack may have different internal resistances, and this inconsistency may lead to fast aging of the whole pack. In order to overcome the shortcomings of existing equalizing charge method, a bidirectional energy transfer mechanism based battery equalizing charge schema is given. We detailed analysis the working principle of equalization circuit and equalization work process, and the program analysis and argument by experiments. Experiments show that the method structure is simple, and it can quickly realize the dynamic transfer of energy between the batteries. The battery power charging imbalance can be effectively solved.
Authors: Asmahani Awang, S.K. Ghoshal, M.R. Sahar, R. Arifin
Abstract: Optimizing of the spectroscopic features of rare earth (RE) doped inorganic glasses via tuneable growth of metallic nanoparticles (NPs) is demanding in plasmonic based nanophotonics. We report the gold (Au) NPs assisted sizeable enhancements in Er3+ luminescence in zinc-sodium tellurite glass. Glasses of the form 70TeO2-20ZnO-10Na2O-(x)Er2O3-(y)Au (x = 0.0 and 1.0 mol%; y = 0.0-0.6 mol% in excess) are synthesized via melt-quenching method and thoroughly characterized. Au concentration dependent variations in the physical and spectroscopic properties of glasses are determined. XRD data confirms the amorphous nature of all samples. UV-Vis-NIR spectra reveal seven absorption bands corresponding to the transitions from ground state (4I15/2) to 4I13/2, 4I11/2, 4I9/2, 4F9/2, 2H11/2, 4F7/2 and 4F5/2 excited states of Er3+. TEM micrograph manifests the existence of non-spherical Au NPs with average size of 8.6 nm. Prominent surface plasmon band of Au NPs is evidenced around 629 nm. Furthermore, Au NPs display a SPR mediated strong absorption in the visible region. Room temperature visible down-conversion emission (under 425 nm excitation) reveal three significant peaks centred at 532 (moderate green represent 2H11/2 4I15/2 transition), 550 (weak green represent 4S3/2 4I15/2 transition) and 588 nm (strong green represent 4S3/2 4I15/2 transition). Glass containing 0.4 mol% of Au exhibiting the highest luminescence intensity is ascribed to the NPs local field enhancement and energy transfer between RE ions and NPs. Variations in the physical properties of glass are explained in terms of the alteration in structures and ligand interactions with Au NPs present in the glass network. The intense field amplification discerned in the vicinity of Au NPs is attributed to the charge accumulation at the surface of the NPs. Surface plasmon resonance (SPR) of Au NPs and energy transfer (ET) from NPs to Er3+ ions are primarily attributed for the observed spectral modification. It is established that our glass composition displaying such significant enhancement may be beneficial for the development of up-converted solid state lasers and other plasmonic devices.
Authors: Ying Gang Zhao, Dong Mei Shi, Jin Liu, Xiao Feng Wang
Abstract: Spectroscopic properties and energy transfer (ET) in Er3+/Eu3+-doped Ga2O3-GeO2 glass have been investigated. Effects of alkali metal and alkaline earth metals ions on thermal stability of Er3+-doped gallate-germanium glass have been investigated. Simultaneously influences of Eu3+ codoping on the optical properties of Er3+-doped Ga2O3-GeO2-Na2O (GN) glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 µm emission intensity and decrease of upconversion (UC) fluorescence with increasing Eu3+ concentration have been observed. The results indicate that the incorporation of Eu3+ into Er3+-doped GN glass can effectively improve 1.53-μm and lower UC luminescence, which makes GN glass more attractive for their use in C-band optical fiber amplifiers.
Authors: E. Gustin, M. Leblans, A. Bouwen, D. Schoemaker
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