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81.
V. M. Zainullina V. L. Volkov N. V. Podvalnaya A. L. Ivanovskii 《Journal of Structural Chemistry》2005,46(2):340-342
The calculations of the electronic structure of layered polyvanadate K2V3O8 were made employing the spin-polarized tight-binding LMTO method. Calculated magnetic moment for K4V6O16 compound phase equals 1.97 μB. V-O interactions were established to be dominating in the chemical bonding generation in this polyvanadate according to the estimated crystal orbital overlap population. The covalent bonds V(2)-V(2) in V(2)2O7 groups and electron density localization on vanadium atoms in isolated pyramids V(1)O5 were found. 相似文献
82.
用真空蒸发沉积的方法制备了纳米稀土(La、Nd、Sm)粒子 BaO介质薄膜.研究表明薄膜的光电发射光谱响应阈值受纳米稀土粒子形状和大小的影响,球形纳米稀土(Sm)粒子 BaO介质薄膜的光谱响应阈值波长为720 nm,条状纳米稀土(La和Nd)粒子 BaO介质薄膜阈值波长分别为650 nm和660 nm.研究得到纳米稀土粒子 介质薄膜等效界面位垒高度在1.7~2.0 eV之间.由于纳米稀土粒子与BaO介质各自逸出功不同,当构成薄膜后使得纳米粒子周围的空间电荷分布发生变化,纳米粒子周围的能带发生弯曲. 相似文献
83.
CAI Shu-Hui LI Jun LIU Chun-WanFujian Institute of Research on the Structure of Matter Chinese Academy of Sciences State Key Laboratory of Structural Chemistry Fuzhou Fujian China 《中国化学》1994,12(5):385-391
The band structures of several analogous superconducting A-15 type solid compounds, Nb3X (X=Si, Ge, Sn, Pb), have been calculated by use of the tight-binding method within the Extended Huckel approximation (EHT). By analysis of their energy bands, densities of states and crystal orbital overlap populations, the dependence of the superconducting transition temperatures (Tc) on the electronic structures and bondings is qualitatively elucidated. 相似文献
84.
F. Munari A. Trisciani G. Mapelli S. Trestianu K. Grob J. M. Colin 《Journal of separation science》1985,8(9):601-606
Two-dimensional chromatography of gasoline by on-line coupled HPLC-HRGC, as described in this paper, allows separate GC analysis of paraffins and aromatics. The GC system contains a retention gap of only 10 m length for introducing HPLC fractions of 100 μl volume. This becomes possible through evaporation of part of the solvent during introduction of the HPLC eluent. This “partially concurrent solvent evaporation” technique allows transfer of large volumes of HPLC eluent into relatively short retention gaps, maintaining the full efficiency of the solvent effects in reconcentrating the bands of the early eluted solutes. 相似文献
85.
Rangel Elidiane C. Cruz Nilson C. da Kayama Milton E. Rangel Rita C. C. Marins Nazir Durrant Steven F. 《Plasmas and Polymers》2004,9(1):1-22
Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2 × 109 to about 0.2 × 109 cm–3 as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E
G, and the surface resistivity, s, fall with increasing P. E
G and s are in the ranges of about 2.0–1.3 eV and 1014–1016 /, respectively. The plasma power also influences the film self-bias, V
b, via a linear dependence, and the effect of V
b on ion bombardment during growth is addressed together with variation in the relative densities of sp2 and sp3 bonds in the films as determined by Raman spectroscopy. 相似文献
86.
87.
Catherine D. Clark Morton Z. Hoffman D. Paul Rillema Quinto G. Mulazzani 《Journal of photochemistry and photobiology. A, Chemistry》1997,110(3):285-290
The photophysics of three complexes of the form Ru(bpy)3−(pypm)2+ (where bpy2,2′-bipyridine, pypm 2-(2′-pyridyl)pyrimidine and P=1, 2 or 3) was examined in H2O, propylene carbonate, CH3CN and 4:1 (v/v) C2H5OH---CH3OH; comparison was made with the well-known photophysical behavior of Ru(bpy)32+. The lifetimes of the luminescent metal-to-ligand charge transfer (MLCT) excited states were determined as a function of temperature (between −103 and 90 °C, depending on the solvent), from which were extracted the rate constants for radiative and non-radiative decay and ΔE, the energy gap between the MLCT and metal-centered (MC) excited states. The results indicate that *Ru(bpy)2(pypm)2+ decays via a higher lying MLCT state, whereas *Ru(pypm)32+ and *Ru(pypm)2(bpy)2+ decay predominantly via the MC state. 相似文献
88.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(17):1978-1988
New donor–π–acceptor (D–π–A) type conjugated copolymers, poly[(4,8‐bis((2‐hexyldecyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophene)‐alt‐(2,5‐bis(4‐octylthiophen‐2‐yl)thiazolo[5,4‐d]thiazole)] (PBDT‐tTz), and poly[(4,8‐bis((2‐hexyldecyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophene)‐alt‐(2,5‐bis(6‐octylthieno[3,2‐b]thiophen‐2‐yl)thiazolo[5,4‐d]thiazole)] (PBDT‐ttTz) were synthesized and characterized with the aim of investigating their potential applicability to organic photovoltaic active materials. While copolymer PBDT‐tTz showed a zigzagged non‐linear structure by thiophene π‐bridges, PBDT‐ttTz had a linear molecular structure with thieno[3,2‐b]thiophene π‐bridges. The optical, electrochemical, morphological, and photovoltaic properties of PBDT‐tTz and PBDT‐ttTz were systematically investigated. Furthermore, bulk heterojunction photovoltaic devices were fabricated by using the synthesized polymers as p‐type donors and [6,6]‐phenyl‐C71‐butyric acid methyl ester as an n‐type acceptor. PBDT‐ttTz showed a high power conversion efficiency (PCE) of 5.21% as a result of the extended conjugation arising from the thienothiophene π‐bridges and enhanced molecular ordering in the film state, while PBDT‐tTz showed a relatively lower PCE of 2.92% under AM 1.5 G illumination (100 mW/cm2). © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1978–1988 相似文献
89.
《Waves in Random and Complex Media》2013,23(1):75-90
In this paper, we seek exact solutions of generalized Zakharov system. We use extended trial equation method to obtain exact solutions of this system. Consequently, we obtain some exact solutions including soliton solutions, rational, Jacobi elliptic and hyperbolic function solutions of this system by using extended trial equation method. 相似文献
90.
Improved estimation of duality gap in binary quadratic programming using a weighted distance measure
We present in this paper an improved estimation of duality gap between binary quadratic program and its Lagrangian dual. More specifically, we obtain this improved estimation using a weighted distance measure between the binary set and certain affine subspace. We show that the optimal weights can be computed by solving a semidefinite programming problem. We further establish a necessary and sufficient condition under which the weighted distance measure gives a strictly tighter estimation of the duality gap than the existing estimations. 相似文献