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排序方式: 共有314条查询结果,搜索用时 171 毫秒
131.
132.
A. Martucci G. Brusatin M. Guglielmi C. Strohhöfer J. Fick S. Pelli G.C. Righini 《Journal of Sol-Gel Science and Technology》1998,13(1-3):535-539
GeO2-SiO2 sol-gel planar waveguides doped with Er were deposited by spinning on silica substrates. P2 O5 or Al2O3 were used as co-dopants to improve erbium dissolution in the GeO2-SiO2 matrix. Multilayer amorphous films were obtained at 600 or 700°C.Er ions in the planar waveguide pumped at 980 nm showed fluorescence features around 1530 nm. Narrow fluorescence spectra (20 nm) and long lifetimes (6 ms) were found in P2O5 co-doped samples, whereas Al2O3 co-doping gave wider spectra (50 nm) with slightly lower lifetimes (5 ms). The quenching concentration in the Al2O3 co-doped samples was 0.9 mol% Er.Heat treatments in CCl4 improve the active properties and the addition of Yb enhances the pump absorption efficiency. 相似文献
133.
The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 5,7-dibromo-8-hydroxyquinoline in the presence of octylphenol poly(ethyleneglycol)ether have been studied by normal and third-derivative spectrophotometry. The proposed method is free of interference of other rare earths. The calibration graphs were linear up to 18 g/ml of neodymium and 21 g/ml of erbium (in the final solution). The derivative molar absorptivities are 395 l.mol–1.cm–1 for neodymium and 3421.mol–1.cm–1 for erbium. The corresponding values of Sandell's sensitivity were 0.36 and 0.49 g.cm–1, respectively. The relative standard deviations evaluated from ten independent determinations of 2.5 g/ml of neodymium and erbium are 1.5 and 3.8% for neodymium and 1.8 and 4.1% for erbium in absence and presence of 70 g of lanthanum, respectively. The detection limits (signal to noise ratio=2) are 0.23 g/ml for neodymium and 0.30 g/ml for erbium. The method has been used for the determination of neodymium and erbium in mixed rare earths with satisfactory results. 相似文献
134.
M. Langlet P. Jenouvrier J. Fick R. Rimet 《Journal of Sol-Gel Science and Technology》2003,26(1-3):985-988
Optically active thin films in the system Y2Ti2O7-Er2Ti2O7 (YETO) have been deposited using the Aerosol-gel process. Depending on the heat-treatment temperature, amorphous or crystalline films could be prepared in the range 600–950°C. The study shows that dilution of erbium ions within a Y2Ti2O7 (YTO) matrix allows to prevent short range distance interactions between those ions and to promote good photoluminescence properties of YETO films. These properties are discussed and compared with those of sol-gel derived silica films doped with erbium. 相似文献
135.
Efficient Discrimination of Single Nucleotide Polymorphisms (SNPs) Using Oligonucleotides Modified with C5‐Pyrene‐Functionalized DNA and Flanking Locked Nucleic Acid (LNA) Monomers 下载免费PDF全文
Oligodeoxyribonucleotides modified with 5‐[3‐(1‐pyrenecarboxamido)propynyl]‐2′‐deoxyuridine monomer X and proximal LNA monomers display higher affinity for complementary DNA, more pronounced increases in fluorescence emission upon DNA binding, and improved discrimination of SNPs at non‐stringent conditions, relative to the corresponding LNA‐free probes across a range of sequence contexts. The results reported herein suggest that the introduction of LNA monomers influences the position of nearby fluorophores via indirect conformational restriction, a characteristic that can be utilized to develop optimized fluorophore‐labeled probes for SNP‐discrimination studies. 相似文献
136.
铒对AZ91镁合金铸态组织与力学性能的影响 总被引:4,自引:0,他引:4
采用X射线衍射、金相观察、扫描电镜及拉伸性能测试,研究了Er的添加对AZ91镁合金的显微组织与力学性能影响。结果显示,基体合金中添加0.98%~1.92%Er后,显微组织主要由-αMg基体相、Mg17Al12相及Al3Er组成。添加Er能有效细化铸态合金的晶粒,使其平均晶粒尺寸从57μm降低到21μm;同时铒的添加改善了基体合金中Mg17Al12相的形态与分布,使AZ91镁合金的室温抗拉强度从162 MPa提高到211 MPa。 相似文献
137.
Andrij Stetskiv Beata Rozdzynska‐Kielbik Renata Misztal Volodymyr Pavlyuk 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(6):506-510
A ternary hexaerbium triacontacobalt enneakaidecasilicide, ErCo5Si3.17, crystallizes as a combination of disordered variants of the hexagonal UCo5Si3 (P63/m) and Yb6Co30P19 (P) structure types and is closely related to the Sc6Co30Si19 and Ce6Rh30Si19 types. The Er, Co and three of the Si atoms occupy sites of m.. symmetry and a fourth Si atom occupies a site of .. symmetry. The environment of the Er atom is a 21‐vertex pseudo‐Frank–Kasper polyhedron. Trigonal prismatic coordination is observed for the Si atoms. The Co atoms are enclosed in heavily deformed cuboctahedra and 11‐vertex polyhedra. Crystallochemistry analysis and the data from electronic structure calculations (TB–LMTO–ASA) suggest that the Er atoms form positively charged cations which compensate the negative charge of the [Co12Si9]m− polyanions. 相似文献
138.
CaTiO3:Er3+微米带由静电纺丝方法制备.用X射线衍射、傅里叶变换红外光谱、拉曼光谱、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)和上转换发光表征所制备的样品.SEM和TEM测试证实所得前躯体微米带尺寸均一,烧后得到的微米带是由纳米粒子组成的.在980 nm激光激发下,CaTiO3:Er3样品发出绿光,绿光发射峰位于546 nm,可归属于Er3+离子的4S3/2 →4I15/2跃迁.当Er3+离子的掺杂浓度提高,因为Er3+离子之间的能量传递,红光发射相对于绿光发射增强. 相似文献
139.
We experimentally demonstrate efficient frequency doubling of a telecom 1560 nm distributed feedback diode laser with a 3 cm long MgO:PPLN waveguide with a conversion coefficient of 114%/W. We investigate optical inhomogeneities by measuring the quasi-phase-matching temperature curve. The -2.7 mW of second-harmonic power at 780 nm is sufficient to detect the Rb D2 features using modulation transfer spectroscopy. The laser frequency is locked to a hyperfine transition of Rb D2 line and typical residual frequency fluctuation of +86 kHz (rms) is achieved within 30 min. Our experimental scheme can be used for realizing robust, compact, and highly accurate Rb stabilized 1560 nm laser systems for fiber-optic communication applications. 相似文献
140.
Olaf R. Ludek 《Tetrahedron》2009,65(41):8461-3851
An enantioselective synthesis of suitably protected (1R,2S,4S,5S)-4-amino-1-(hydroxymethyl)bicyclo[3.1.0]hexan-2-ol, a key starting material for the synthesis of conformationally locked carbocyclic nucleosides, including the antiviral active North-methanocarbathymidine, is reported. Starting from 2-deoxyribose the target Boc-protected amine was prepared in 33% overall yield under conditions that are ecologically friendlier than previous methods. 相似文献