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利用等离子体增强化学气相沉积技术制备了a-Si ∶H/SiO2多量子阱结构材料.对a-Si ∶H/SiO2多量子阱样品分别进行了3种不同的热处理,其中样品经1100 ℃高温退火可获得尺寸可控的nc-Si:H/SiO2量子点超晶格结构,其尺寸与非晶硅子层厚度相当.比较了a-Si ∶H/SiO2多量子阱材料与相同制备工艺条件下a-Si ∶H材料的吸收系数,在紫外/可见短波段前者的吸收系数明显增大,光学吸收边蓝移,说明该材料
关键词:
多量子阱
量子限制效应
光学吸收
能带结构 相似文献
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选择性萃取对沉积物非残渣态、粘土矿物结构及吸附特性的影响 总被引:1,自引:0,他引:1
用NH2OH·HCl, (NH4)2C2O4和H2O2对表层沉积物中非残渣态的Mn氧化物、Fe/Mn氧化物和有机质进行选择性化学萃取, 同时提取粘土矿物, 并对提取前后的表层沉积物样品进行了比表面积、FTIR、ESEM和XRD等分析. 结果表明, 萃取后沉积物的比表面积显著增大, 沉积物颗粒的分散度随之增大, 晶体边缘逐渐清晰, 棱角逐渐分明, 但沉积物的XRD和FTIR谱图变化不大, 原因在于XRD和FTIR谱图中的特征峰主要是由矿物组分产生的. 萃取后随着沉积物分散度的增大, 晶体颗粒表面粗糙度减弱, 沉积物的吸附能力降低, 表明颗粒表面特征对重金属的吸附起到一定作用; 而沉积物的比表面积与沉积物吸附能力之间的反比关系说明沉积物主要吸附组分对其吸附的贡献远远大于沉积物表面与孔隙结构的贡献. 相似文献
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Wei Yan An-kuo Li Chain-shu Hsub Zhi-cheng Zhang Mei-xiang Wan College of Chemical Engineering Xi''''an Jiaotong University Xi''''an China Department of Applied Chemistry National Chiao Tung University Hsinchu China Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing China 《高分子科学》2001,(5):499-502
A novel small band-gap conjugated polymer - poly [(3-acetylpyrrole-2, 5-diyl)(4-dimethylaminobenzyliene)(3 -acetylpyrrolequinodimethane-2, 5-diyl)] (PAPDMABE) - and its precursor were synthesized by a simple method andcharacterized by ~1H-NMR, FT-IR, TGA and UV-VIS. The polymer can be dissolved in strong polar solvents such as DMSO,DMF or NMP. The band-gap energy of PAPDMABE was found to be 0.95 eV. The conductivity of doped products withiodine falls in the range of a semiconductor. 相似文献
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A novel copper-catalyzed dual oxidative benzylic C–H aminations of methylarenes with 2-aminobenzoketones in the presence of ammonium acetate was developed. This reaction represents a new avenue for 2-arylquinazolines with good yields. A key intermediate was detected and the kinetics isotope effect(KIE) indicated that C–H bond cleavage was the rate-determining step. 相似文献
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The microstructural variation near surface of nano elastic materials is analyzed based on different potentials. The atomic/molecular mechanism underlying the variation and its effect on elastic modulus are such that the nature of long-range interactions (attractive or repulsive) in the atomic/molecular potentials essentially governs the variation near surface (looser or tighter) and results in two opposite size effects (decreasing or increasing modulus) with decreasing size. 相似文献
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Yen-Che Chiang Yi-Zhe Hsub Ruoh-Chyu Ruaan Ching-Jung Chuang Kuo-Lun Tung 《Journal of membrane science》2009
Four nanofiltration membranes, two negatively and two positively charged, were fabricated by interfacial polymerization. Three different amines, ethylenediamine (EDA), diethylenetriamine (DETA), and hyperbranched polyethyleneimine (PEI) were selected to react with two acyl chlorides, trimesoyl chloride (TMC) and terephthaloyl chloride (TPC). The two membranes containing hyperbranched PEI, PEI/TPC and PEI/TMC, are positively charged at the operational pH. But the other two membranes, EDA/TMC and DETA/TMC, are negatively charged. It is found that the two PEI membranes own special rejection characters during nanofiltration. The PEI/TPC membrane has a similar pore size to the EDA/TMC membrane but owns simultaneously the higher salt rejection and permeation flux. The PEI/TMC has a pore size as large as 1.5 nm and still has a higher NaCl rejection than the EDA/TMC membrane of which the pore size as small as 0.43 nm. We consider that the special rejection characters are derived from the special structure of PEI. The hyperbranched structure allows some of the charged amine groups drifting inside the pores and interacting with the ions in the pathway. The drifting amines increase salt rejection but have little effect on water permeation. It implies that a high flux and high rejection membrane for desalting can be obtained by attaching freely rotating charged groups. 相似文献
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The quality of the novelty filter image is investigated at different
intensities of the incident blue and yellow beams irradiating a
bacteriorhodopsin (bR) film. The relationship between the transmitted blue
beams and the incident yellow beams is established. The results show that
the contrast of the novelty filter image depends on the lifetime of longest
lived photochemical state (M state). These results enable one to identify
the direction of a moving object and to improve the quality of the novel
filter image by prolonging the lifetime of M state. 相似文献
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