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91.
IR and UV-absorption spectra, and the thermally stimulated currents of pure and Rhodamine-6G-doped poly(acrylonitrile–butadiene–styrene) (Rhdoped ABS) films were investigated. Structural characteristics could be specified from these techniques. Both IR and UV-absorption studies revealed a modification of the structure of ABS on blending with Rhodamine 6G: Rh molecules are partially dispersed in the ABS matrix and partially attached as side groups to the ABS backbone. Thermally stimulated depolarization current (TSDC) studies confirmed this result. The results revealed that incorporation of Rh 6G in ABS locks the dipole in the ABS matrix after electric poling. The TSDC spectra have been found, depending on the polarization temperature, to be characterized by three peaks. The phenomenon of the existence of these current maxima is discussed and analysed in terms of dipolar and ionic relaxations. 相似文献
92.
《Ceramics International》2021,47(18):25708-25720
Tb3+/Dy3+ co-doped CaLa2(WO4)4 (CLW: Tb3+/Dy3+) and its derivatives were synthesized by the sol-gel method. The morphology, thermal, structure and luminescent-optical properties the as-prepared light-emitting phosphors were characterized by utilizing scanning electron microscopy (SEM), differential thermal analysis (DTA)-thermogravimetric analysis (TG), X-ray diffraction (XRD) and radioluminescence (RL or X-ray luminescence) - photoluminescence (PL) –thermoluminescence (TL or TSL) - optical absorption spectrometry. The Tb3+ and Dy3+ ions were singly or doubly doped and the results were examined in detail. Moreover, for these phosphors, the energy transfer mechanisms which depend on RL and PL spectra were determined. The samples excited by X-ray demonstrate characteristic luminescence peaks of Dy3+ (422, 480, 575, 663 and 747 nm) and Tb3+ (489, 544, 586, 620, 652 and 675 nm). These emissions are similar for RL and PL measurements. It could be said that the energy transfer efficiency of the host material is perfect for rare-earth ions. The synthesized phosphors exhibit various colors from yellow to blue under UV excitation. The optical band gaps of host CLW, CLW: Tb3+, CLW: Dy3+ and co-doped CLW: Tb3+/Dy3+ were calculated at values 3.83 eV, 3.44 eV, 3.64 eV and 3.52 eV, respectively. From the results obtained, the CaLa2(WO4)4: Tb3+, Dy3+phosphors may be one of the potential candidates for light-emitting diode. 相似文献
93.
M. Romand F. Gaillard M. Charbonnier N. S. Prakash L. Deshayes I. Linossier 《The Journal of Adhesion》1995,55(1):1-16
A number of surface modification methods using mechanical, chemical, electrochemical or physical processes have commonly been employed to treat adherend surfaces and improve adhesion in various bi- or multi-layered systems which play a key role in many advanced technologies. Results reported in this review paper deal more particularly with components of polymer-metal systems and provide typical examples of surface analysis obtained by x-ray photoelectron spectrometry (XPS), ion scattering spectrometry (ISS), low-energy electron induced x-ray spectrometry (LEEIXS), optically stimulated electron emission (OSEE) and Fourier transform infra-red spectrometry (FTIR). These examples concern, on the one hand, metallic adherends (aluminum, stainless steel, zinc-coated steel, gold) the surfaces of which were modified by cleaning, etching, oxidation, conversion or chemical grafting and, on the other hand, bonded joints (polyester-steel and epoxy-aluminum systems) which were delaminated using a peel test and a three-point flexure test, respectively. 相似文献
94.
A new blue-emitting nanophosphor of Eu2+-activated BaCa2Al8O15 was synthesized by the Pechini method. The phosphors were investigated by X-ray powder diffraction (XRD) measurement and confirmed to be a pure crystalline phase of BaCa2Al8O15. The photoluminescence excitation and emission spectra, the luminescence decay and the color coordinates were taken to investigate the luminescence characteristics. The dependence of luminescence intensities BaCa2Al8O15:Eu2+ on the doping concentrations was investigated. This nanophosphor can be efficiently excited by UV light and presents bright blue luminescence. Under the same conditions, the light yield of BaCa2Al8O15:Eu2+ is about 1.2 times higher than that of blue-emitting phosphor BaMgAl10O17:Eu2+. Eu2+-activated BaCa2Al8O15 nanophosphor exhibits the long-lasting phosphorescence, which was analyzed by measuring the afterglow decay curves. The co-doped Eu3+ ions and some defects were suggested to be the possible trap-centers. 相似文献
95.
It is shown that for a front-to-back geometry of irradiation with photons and neutrons when monitoring doses in accordance
with the radiation safety standard NRB-99 or doses in critical organs using previous standards, the requirements imposed on
the energy dependence of the sensitivity of dosimeters have hardly changed since 1960. However, the requirements were quite
different for photons when monitoring the exposure dose using previous standards.
Translated from Izmeritel’naya Tekhnika, No. 2, pp. 49–55, February, 2009. 相似文献
96.
Fang‐Ming Hsu Chen‐Han Chien Ching‐Fong Shu Chin‐Hung Lai Cheng‐Chih Hsieh Kang‐Wei Wang Pi‐Tai Chou 《Advanced functional materials》2009,19(17):2834-2843
Highly efficient blue electrophosphorescent organic light‐emitting diodes incorporating a bipolar host, 2,7‐bis(diphenylphosphoryl)‐9‐[4‐(N,N‐diphenylamino)phenyl]‐9‐phenylfluorene (POAPF), doped with a conventional blue triplet emitter, iridium(III) bis[(4,6‐difluoro‐phenyl)pyridinato‐N,C2´]picolinate (FIrpic) are fabricated. The molecular architecture of POAPF features an electron‐donating (p‐type) triphenylamine group and an electron‐accepting (n‐type) 2,7‐bis(diphenyl‐phosphoryl)fluorene segment linked through the sp3‐hybridized C9 position of the fluorene unit. The lack of conjugation between these p‐ and n‐type groups endows POAPF with a triplet energy gap (ET) of 2.75 eV, which is sufficiently high to confine the triplet excitons on the blue‐emitting guest. In addition, the built‐in bipolar functionality facilitates both electron and hole injection. As a result, a POAPF‐based device doped with 7 wt% FIrpic exhibits a very low turn‐on voltage (2.5 V) and high electroluminescence efficiencies (20.6% and 36.7 lm W?1). Even at the practical brightnesses of 100 and 1000 cd m?2, the efficiencies remain high (20.2%/33.8 lm W?1 and 18.8%/24.3 lm W?1, respectively), making POAPF a promising material for use in low‐power‐consumption devices for next‐generation flat‐panel displays and light sources. 相似文献
97.
本研究是建立阻断股骨头动脉的股骨头缺血模型,通过分别阻断实验兔股骨头旋股内、外侧动脉,观察99mTc-MDP骨显像对于股骨头血流、代谢变化,及组织学改变.将实验兔分成三组:A组,结扎旋股内、外侧动脉;B组,结扎旋股内侧动脉;C组,结扎旋股外侧动脉.所有实验兔在术前均由耳缘静脉注入99mTc-MDP37 MBq,然后于术后两小时至八周应用SPECT检测实验侧股骨头(E头)、实验侧股骨干(E干)、对照侧股骨头(C头)、对照侧股骨干(C干)放射性计数,并计算比值和动态检测股骨头血流量及代谢的改变.结果是A组B组骨显像结果相同,手术当日及术后三日均可见兔实验侧股骨头放射性缺损,于术后一周开始出现放射性浓聚,至术后四周达高峰,术后八周仍有明显放射性浓聚,呈持续性高代谢反应状态.C组各时期三相骨显像结果与A、B组不同,手术当日可见兔实验侧股骨头放射性缺损,于术后三日即开始出现放射性浓聚,术后一周、四周均可见放射性浓聚,于术后八周即完全恢复.①E 头/C头比值:1.020±0.063,C头/C干比值:2.721±0.086.②A组和B组结扎旋股动脉术后两小时和三天E头/C 头和E 头/E 干比值明显下降,术后一周至八周血供重建,两组间无显著性差异(P>0.05);③C组E 头/C 头和E 头/E干比值轻度下降,术后三天血供重建,比值增高不显著,与前两组之间均有显著性差异(P<0.05).这说明:1.旋股内侧动脉及其分支为股骨头主要供血动脉;2.99mTc-MDP骨显像定量分析是评价ANFH的好方法. 相似文献
98.
研究存在Kerr介质时,耦合双原子与单模压缩真空场双光子跃迁相互作用系统平均光子数的时间演化规律,讨论Kerr介质与光场的耦合强度和原子间偶极-偶极相互作用对平均光子数的影响. 相似文献
99.
利用受激布里渊散射相位共轭镜克服激光棒热效应的实验研究 总被引:4,自引:4,他引:4
利用受激布里渊散射(SBS)相位共轭镜(PCM)能克服单棒Nd:YAG的热效应.从而使光束质量提高到衍射极限。对于具有一定的热效应影响的YAG激光棒.采用上作在接近临界稳定区的凹-凸腔作为起始腔.通过对受激布里渊散射相位共轭腔进行优化设计,在抽运能量为10J,重复频率为5Hz时,得到稳定输出的能量为20mJ,脉宽为11.8ns的近衍射极限的高质量激光脉冲。 相似文献
100.
研究了激光二极管(LD)抽运的自拉曼Nd∶YVO4调Q激光器的特性。Nd∶YVO4晶体同时作为激光介质和拉曼晶体,通过声光调Q技术,产生了1176 nm的拉曼激光。测量了平均输出功率、脉冲宽度和单脉冲能量随抽运功率和脉冲重复率的变化。典型的1064 nm基频光和1176 nm拉曼光脉冲的脉冲宽度分别为26.3 ns和9.0 ns。在脉冲重复率为20 kHz,抽运功率为8.46 W时,产生了平均功率为0.384 W的1176 nm光的输出,光-光转换效率为4.54%。使用速率方程对自拉曼Nd∶YVO4调Q激光器特性进行了理论研究,把脉冲重复率为10 kHz,20 kHz,30 kHz时拉曼光单脉冲能量和脉冲宽度的实验值与理论值进行了比较,结果基本相符。 相似文献