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浏览/检索结果: 共7条，第1-7条 帮助 限定条件 内容类型：会议论文    专题：长春光学精密机械与物理研究所    第一署名单位    第一作者单位    通讯作者单位     已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 Influence of high temperature annealing in nitrogen on upconversion luminescence of -NaYF4: Yb3+, Er3+ hexagonal sub-microplates (EI CONFERENCE) 会议论文 2012 International conference on Function Materials and Nanotechnology, FMN 2012, May 19, 2012 - May 20, 2012, Zhengzhou, China Zhao J.; Jia T.; Kong X. 收藏  |  浏览/下载：15/0  |  提交时间：2013/03/25 The pure -NaYF4: Yb3+  Er3+ hexagonal sub-microplates were successfully prepared by the combination of coprecipitation and hydrothermal methods using sodium citrate as chelator. The size of them is about 600 nm 400 nm (side length thickness). The obtained sample was divided into two parts and one of them was annealed in nitrogen at 300 C for 2 hours. The crystal structure of the -NaYF4: Yb3+  Er3+ hexagonal sub-microplates before and after annealing treatment is hexagonal phase. Under the excitation of 980 nm diode laser  the upconversion luminescence intensity the sample after annealing is much stronger than that of the sample without annealing treatment. High temperature annealing process improved the crystallization of the sample  resulting in the decrease of the nonradiative relaxation and the enhancement of the upconversion luminescence. (2012) Trans Tech Publications  Switzerland.   Influence of sensitizer concentration on the upconversion luminescence of NaYF4: Yb3+, Er3+ nanoparticles (EI CONFERENCE) 会议论文 2012 2nd International Conference on Machinery, Materials Science and Engineering Applications, MMSE 2012, June 16, 2012 - June 17, 2012, Wuhan, China Zhao J.; Shi D.; Zhao Y.; Kong X. 收藏  |  浏览/下载：14/0  |  提交时间：2013/03/25 A series of NaYF4: Yb3+  Er3+ nanoparticles with different doping concentration were successfully prepared by the combination of coprecipitation and hydrothermal methods using sodium citrate as chelator. Upconversion luminescence can be observed in all of the samples at room temperature. Fixed the Er3+ concentration with 1 mol% unchanged  the effect of the Yb3+ concentration on the upconversion luminescence of NaYF4: Yb3+  Er3+ samples were studied when the doped Yb3+ concentrations were 0 mol%  1 mol%  2 mol%  5 mol%  10 mol% and 20 mol%  respectively. As increasing the Yb 3+ concentration  the total intensity of the upconversion luminescence of the samples is increasing while the ratio of red to green emission increases firstly and then decreases. The maximum ratio value is 22.1 when the Yb3+ concentration is 10 mol%. It is found that the cross relaxation and cooperative sensitization effect are the reasons for the phenomenon above. (2012) Trans Tech Publications.   Mechanisms of energy transfer in Pr3+ and Cr3+ codoped SrAl12O19 phosphor (EI CONFERENCE) 会议论文 209th ECS Meeting, May 7, 2006 - May 12, 2006, Denver, CO, United states Nie Z.; Zhang J.; Ren X. G.; Zhang G.; Wang X.-J. 收藏  |  浏览/下载：14/0  |  提交时间：2013/03/25 A two-step energy transfer was observed in Pr3+ and Cr 3+ codoped SrAl12O19 phosphor  which results in a two-photon luminescence for one UV/vacuum-UV photon absorbed. For one Pr 3+ ion excited to the lowest 4f5d states  two Cr3+ ions may be excited and emit two red photons due to 2E- 4A2 transitions of the Cr3+ ions  Cr 3+ ions can be excited into the 4T1(F) levels by cross relaxation of Pr3+ 1S0- 1I6 or by direct energy transfer from Pr3+ 3P0  1 states. The mechanisms of the two-step energy transfer process were studied based on spectra and lifetime measurements. copyright The Electrochemical Society.   Energy transfer processes on both Er+ ion concentration and excitation densities in Yb3+-Er3+ codoped LaF3 matrix (EI CONFERENCE) 会议论文 Zhang J.; Qin W.; Zhao D.; De G.; Zhang J.; Wang Y.; Cao C. 收藏  |  浏览/下载：14/0  |  提交时间：2013/03/25 The effects of both Er3+ ion concentration and excited density upon frequency upconversion fluorescence emissions in Er3+/Yb 3+-codoped LaF3 powder are investigated. The results reveal that a higher Er3+ concentration can induce not only upconversion emission enhancements but also the changes among the relative intensities of the 407  519  539 and 651 nm radiation transitions as the samples are excited within the ranges of 20 to 700 mW with 978 nm laser diode (LD) as an excitation source. The changes are described by a schematic level model with the cross-relaxation processes between Er3+ ions and a series of dynamic equations that take into account the population of temperature dependent in Er3+. 2006 Elsevier B.V. All rights reserved.   Energy transfer in Pr3+- and Cr3+-codoped SrAl 12O19 system (EI CONFERENCE) 会议论文 Nie Z.; Zhang J.; Zhang X.; Luo Y.; Lu S.; Wang X. 收藏  |  浏览/下载：14/0  |  提交时间：2013/03/25 The energy transfer processes in Pr3+- and Cr 3+-codoped SrAl12O19 system are studied experimentally. The transfer can convert the 1S0 ultraviolet fluorescence of Pr3+ into the red emission of Cr 3+. The 3P0 state  which may be populated by 1S0&rarr1I6 emission  can also act as a donor state in the transfer to Cr3+. Cross-relaxation process is reported firstly in energy transfer between the pair of Pr 3+-Cr3+ in SrAl12O19 system. Two-step energy transfer is discussed  which involves two visible photons for each vacuum ultraviolet photon absorbed. 2006 Elsevier B.V. All rights reserved.   High energy long duration frequency-doubled Nd:YAG laser and application to veins occlusion (EI CONFERENCE) 会议论文 High-Power Lasers and Applications III, November 8, 2004 - November 11, 2004, Beijing, China Zhang L.; Yang G.; Li D.; Lu Q.; Gu H.; Zhu L.; Zhao Z.; Li X.; Tang Y.; Guo J. 收藏  |  浏览/下载：20/0  |  提交时间：2013/03/25 Laser treatment represents an attractive option to other methods of vessel diseases especially varicose veins. A long pulse (30-50ms) 532nm laser (Fig.1) is used in our experiments with the pulse duration matching the thermal relaxation time of the vessels and the green laser matching the absorption spectrum peak of the blood. Laser irradiates nude vein vessels directly or exterior skin to finish operation faster and to acquire the practical data for upper enteron varicose vein treatment in several animal experiments performed in vivo. The 5J-energy pulse allows us to finely occlude rabbit or dog's vein vessels up to 2 mm in diameter when irradiating them off external skin (Fig.2). Blood vessels are occluded at once and later biopsy specimens show the immediate and long-term lasting occlusion effect. While irradiating vessels directly (Fig.3)  the vessels are usually irradiated to perforate  detailed causes are still under investigation. Animal experiments show long pulse green laser therapy is a safe and effective solution to the vein's occlusion  which promises such laser with high energy of each pulse and 30-50 ms duration is an ideal candidate for vessel diseases treatment.   Characterization of ZnO/Mg0.12Zn0.88O heterostructure grown by plasma-assisted molecular beam epitaxy (EI CONFERENCE) 会议论文 13th International Conference on Molecular Beam Epitaxy, August 22, 2004 - August 27, 2004, 13th International Conference on Molecular Beam Epitaxy, August 22, 2004 - August 27, 2004 Lu Y. M.; Wu C. X.; Wei Z. P.; Zhang Z. Z.; Zhao D. X.; Zhang J. Y.; Liu Y. C.; Shen D. Z.; Fan X. W. 收藏  |  浏览/下载：21/0  |  提交时间：2013/03/25 In this paper  Mg0.12Zn0.88O/ZnO heterostructures were fabricated on c-plane sapphire (Al2O3) substrates by plasma-assisted molecular beam epitaxy (P-MBE). The quality of the Mg 0.12Zn0.88O alloy thin film was characterized by X-ray diffraction (XRD) and reflection high-energy electron diffraction (RHEED). Optical properties of the Mg0.12Zn0.88O/ZnO heterostructure were studied by absorption and photoluminescence (PL) spectra. At room temperature (RT)  Mg0.12Zn0.88O/ZnO heterostructures show two absorption edges originating from ZnO and Mg 0.12Zn0.88O layers  respectively. In PL spectra  two ultraviolet emission bands related to the ZnO layer and the Mg 0.12Zn0.88O layer were observed. The emission band from Mg0.12Zn0.88O layer dominates at moderately lower temperature  and the luminescence of ZnO becomes gradually important with increasing temperature. This is suggested to exist as a potential barrier in the interface and to restrict the relaxation of the carriers from the Mg 0.12Zn0.88O layer to ZnO layer. As the thickness of ZnO layer decreases  the emission from the Mg0.12Zn0.88O layer becomes weaker and weaker. When the ZnO thickness is up to 2 nm  only the luminescence of the ZnO layer is observed at RT. The quenching of the emission corresponding to the MgZnO layer indicates the existence of a strong injection process in the samples with thinner ZnO layer. 2005 Elsevier B.V. All rights reserved.