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81.
G. Kocher-Oberlehner W. Jantsch L. Palmetshofer A. Ulyashin 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):347
Erbium (Er)- and oxygen (O)-doped Cz–Si was additionally doped with hydrogen, using plasma enhanced chemical vapour deposition. Photoluminescence (PL) spectra show a large enhancement especially for samples treated with solid phase epitaxy before hydrogenation and annealing at 900°C later. Secondary ion mass spectroscopy measurements give evidence for an enhanced diffusion of O and Er at this temperature towards the surface. Etching shows that the PL does not stem from the heavily doped surface layer but from a deeper region with lower Er concentration. This conclusion is supported by the appearance of the so-called “cubic” centre with low solubility. Comparing the PL yield of the hydrogenated samples to that of samples with similar Er volume concentration but without hydrogenation still gives a large enhancement. We thus conclude that hydrogen can enhance the solubility of the cubic centre in Si:Er,O. 相似文献
82.
林诒勋 《高校应用数学学报(英文版)》2003,18(3):361-369
§ 1 IntroductionThe cutwidth problem for graphs,as well as a class of optimal labeling and embed-ding problems,have significant applications in VLSI designs,network communicationsand other areas (see [2 ] ) .We shall follow the graph-theoretic terminology and notation of [1 ] .Let G=(V,E)be a simple graph with vertex set V,| V| =n,and edge set E.A labeling of G is a bijec-tion f:V→ { 1 ,2 ,...,n} ,which can by regarded as an embedding of G into a path Pn.Fora given labeling f of G,th… 相似文献
83.
Jin-Mok Hur Chung-Seok Seo Sun-Seok Hong Dae-Seung Kang Seong-Won Park 《Reaction Kinetics and Catalysis Letters》2003,80(2):217-222
The concept of a novel electrochemical reduction process for the treatment of spent nuclear fuels in Li2O-LiCl molten salt was proposed and fresh tests using U3O8 powder were carried out to elucidate the reaction mechanism and verify the feasibility of the process. Electrolysis of Li2O and reduction of U3O8 powder took place simultaneously at the cathode part of the electrolysis cell via a catalytic EC mechanism and the conversion of U3O8 to U metal was more than 99%.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
84.
用密度泛函B3LYP/ 6 3 1G(d)方法 ,对质子化丙酮分子团簇 (CH3COCH3) nH+ (n =1~ 7)弱相互作用体系进行了全自由度能量梯度优化 ,得到了该系列团簇的稳定结构及其对应的体系能量 .通过对构型的分析得出了质子化丙酮分子团簇 (CH3COCH3) nH+ (n =1~ 7)的生长规律 .计算了中性丙酮分子团簇体系的质子亲合能并总结出其变化趋势 .分析讨论了质子化团簇的红外振动光谱 ,发现质子化团簇的振动光谱普遍较中性环型团簇的振动光谱复杂 ,最强的振动峰来源于质子在溶剂壳中两个氧原子之间的振动 ,而且随着团簇尺寸的增加羰基的伸缩振动峰的数目也随之增多 相似文献
85.
I. El-Kady R. Biswas Y. Ye M. F. Su I. Puscasu Martin Pralle E. A. Johnson J. Daly A. Greenwald 《Photonics and Nanostructures》2003,1(1):69-77
In this work, we present both the theoretical basis as well as supporting experimental measurements for development of a novel mid-infrared thermally stimulated narrow band emitter with a spectral bandwidth of less than 10%. To achieve this, we utilize a metallized-surface 2D photonic crystal of air voids in a silicon background with hexagonal structure symmetry. Our results are based on the generation of discrete surface plasmon (SP) modes in the thin metallized layer residing on the top surface. This yields a series of adequately spaced discrete peaks in the reflection spectrum, dominated by a single sharp feature corresponding to the lowest plasmon order, in an otherwise uniform highly reflective spectrum (>90%) over most of the IR spectrum. This, in turn, gives rise to a sharp absorption feature with a correspondingly narrow thermal emission peak in the emission spectrum. Transfer matrix calculations simulate well both the position and strengths of the absorption peaks. By altering the period of the surface photonic lattice, the SP peak and emissive band can be tuned to the desired wavelength. These devices promise a new class of tunable infrared emitters with high power in a narrow spectral bandwidth. Such narrow band sources are critical to achieving high efficiency gas sensors. 相似文献
86.
Hyun Chul Choi Min Kyu Lee Hyun Joon Shin Seung Bin Kim 《Journal of Electron Spectroscopy and Related Phenomena》2003,130(1-3):85-96
To investigate the formation of a solid electrolyte interface (SEI) on the Li1+xV3O8 electrode surface in the thermodynamic stability range of the organic electrolyte, we applied scanning photoelectron microscopy (SPEM) to a pristine electrode and to an electrode after ten cycles. The F K-edge absorption spectrum of the cycled electrode showed that LiF forms on the electrode surface during the lithium insertion–extraction process in the Li1+xV3O8/Li cell. The photoelectron spectrum for the cycled electrode showed intense spectral features corresponding to Li 1s, F 2s, F 2p, and P 2p electron signals, whereas these spectral features were of negligible intensity for the pristine electrode. The above results give strong support for the formation of an SEI that consists of LiF and compounds containing phosphorus during operation of the battery. The SPEM images also revealed that the fluorine distribution on the surface of the cycled electrode was inhomogeneous. 相似文献
87.
This paper presents a quantum chemical calculation of native (2–7 fructoside residues) and chemically modified (2–4 fructoside residues) levan molecule models. A levan modification was carried out by oxidation and the following reduction or hyrdazonation of the fructoside rings. The conformational particularity and reaction ability was studied for the native and for the modified levan molecules. 相似文献
88.
Z. J. Yu L. J. Liu R. X. Zhuo 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):13-21
The ring‐opening polymerization of ε‐caprolactone (ε‐CL), initiated by carboxylic acids such as benzoic acid and chlorinated acetic acids under microwave irradiation, was investigated; with this method, no metal catalyst was necessary. The product was characterized as poly(ε‐caprolactone) (PCL) by 1H NMR spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and gel permeation chromatography. The polymerization was significantly improved under microwave irradiation. The weight‐average molecular weight (Mw) of PCL reached 44,800 g/mol, with a polydispersity index [weight‐average molecular weight/number‐average molecular weight (Mw/Mn)] of 1.6, when a mixture of ε‐CL and benzoic acid (25/1 molar ratio) was irradiated at 680 W for 240 min, whereas PCL with Mw = 12,100 and Mw/Mn = 4.2 was obtained from the same mixture by a conventional heating method at 210 °C for 240 min. A degradation of the resultant PCL was observed during microwave polymerization with chlorinated acetic acids as initiators, and this induced a decrease in Mw of PCL. However, the degradation was hindered by benzoic acid at low concentrations. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 13–21, 2003 相似文献
89.
90.
Syed M. Alam Donald E. Troxel Carl V. Thompson 《Analog Integrated Circuits and Signal Processing》2003,35(2-3):199-206
In this paper, we describe a comprehensive layout methodology for bonded three-dimensional integrated circuits (3D ICs). In bonded 3D integration technology, parts of a circuit are fabricated on different wafers, and then, the wafers are bonded with a glue layer of Cu or polymer based adhesive. Using our layout methodology, designers can layout such 3D circuits with necessary information on inter-wafer via/contact and orientation of each wafer embedded in the layout. We have implemented the layout methodology in 3DMagic. Availability of 3DMagic has led to interesting research with a wide range of layout-specific circuit evaluation, from performance comparison of 2D and 3D circuits to layout-specific reliability analyses in 3D circuits. Using 3DMagic, researchers have designed and simulated an 8-bit encryption processor mapped into 2D and 3D FPGA layouts. Moreover, the layout methodology is an essential element of our ongoing research for the framework of a novel Reliability Computer Aided Design tool, ERNI-3D. 相似文献