钕敏化多层壳纳米结构的增强型染料敏化上转换发光

对于稀土离子掺杂的上转换发光,由于稀土离子吸收截面小、吸收范围窄,导致其发光强度受限.最近,在稀土上转换纳米粒子的表面连接近红外染料分子敏化发光,被证实是提高上转换发光强度的有效策略.然而,将染料分子连接经典的稀土Yb掺杂纳米粒子,并不能有效利用染料分子的敏化能力.针对这一问题,本文通过高温热分解法成功制备了Nd3+敏...     

Molecular Simulation on Competitive Adsorption Differences of Gas with Different Pore Sizes in Coal

Micropores are the primary sites for methane occurrence in coal. Studying the regularity of methane occurrence in micropores is significant for targeted displacement and other yield-increasing measures in the future. This study used simplified graphene sheets as pore walls to construct coal-structural models with pore sizes of 1 nm, 2 nm, and 4 nm. Based on the Grand Canonical Monte Carlo (GCMC) and molecular dynamics theory, we simulated the adsorption characteristics of methane in pores of different sizes. The results showed that the adsorption capacity was positively correlated with the pore size for pure gas adsorption. The adsorption capacity increased with pressure and pore size for competitive adsorption of binary mixtures in pores. As the average isosteric heat decreased, the interaction between the gas and the pore wall weakened, and the desorption amount of CH₄ decreased. In ultramicropores, the high concentration of CO₂ (50–70%) is more conducive to CH₄ desorption; however, when the CO₂ concentration is greater than 70%, the corresponding CH₄ adsorption amount is meager, and the selected adsorption coefficient S_CO2/CH4 is small. Therefore, to achieve effective desorption of methane in coal micropores, relatively low pressure (4–6 MPa) and a relatively low CO₂ concentration (50–70%) should be selected in the process of increasing methane production by CO₂ injection in later stages. These research results provide theoretical support for gas injection to promote CH₄ desorption in coal pores and to increase yield.     

基于密度泛函的伪麻黄碱拉曼光谱性质研究

研究伪麻黄碱的拉曼光谱和吸附在纳米银基底上的表面增强拉曼光谱(SERS),利用密度泛函理论B3LYP/6-311G++(d, p)方法对伪麻黄碱分子进行了计算,得到了分子构型信息和理论拉曼光谱,用Gaussview软件对分子振动模式进行了全面的归属,在伪麻黄碱的表面增强拉曼光谱中,采用了自组装方法获得了团簇银纳米表面增强基底,实现了很好的增强效应.实验结果表明：伪麻黄碱的拉曼光谱计算结果和实验结果基本一致,理论计算为伪麻黄碱分子振动峰位的归属提供了重要的依据,伪麻黄碱分子与银纳米表面化学吸附,苯环垂直于纳米基底表面,研究结果为伪麻黄碱的拉曼光谱检验分析提供了理论依据,也为苯丙胺类毒品的光谱分析研究提供了参考.     

彩色表面等离子体共振成像初探

自主设计并建立了彩色表面等离子共振成像(Color SPRI, CSPRI)实验系统, 并结合利用自己编制的软件开展了相关研究, 成功地观测到溶液和蛋白点阵的彩色图像. 这些结果显示, CSPRI有可能成为生物分子微点阵(或生物芯片)的一种新型的彩色显示手段.     

苯硫酚吸附在新型Ag-Au合金纳米粒子上的表面增强拉曼光谱研究

以柠檬酸钠同时还原制备的Ag-Au合金纳米粒子为种子,用盐酸羟胺进一步使其生长得到粒径为40～60 nm的新型Ag-Au合金纳米粒子,采用UV-Vis光谱和TEM对纳米种子和再生长后的纳米粒子分别进行表征。两种粒子的UV-Vis光谱均只观察到一个等离子体共振峰,其频率随金的摩尔分数(x_Au)增加而红移,且TEM图像表明这两种粒子的颜色均一,因此判断这两种粒子均为合金结构。以苯硫酚为探针分子,研究了该新型合金纳米粒子的表面增强拉曼光谱(SERS),结果表明吸附了苯硫酚的合金纳米粒子的紫外最大吸收峰红移,并在近红外区出现聚集体的吸收峰。在632.8 nm波长激发下,由于表面等离子体共振效应Au上的SERS信号最强,而合金纳米粒子上的SERS信号随x_Au增大而增强。     

用锌有机源和CO2/H2混合气源PECVD沉积ZnO薄膜

在等离子体作用下,以CO2/H2混合气为氧源,Zn(C2H5)2锌为锌源,在单晶硅上生长出高度择优取向的氧化锌薄膜。X射线衍射分析表明,薄膜为六方结构,c轴高度择优;原子力显微镜观察到晶粒是有规律地按六方排布,薄膜的表面粗糙度较小;从光致发光谱还发现在380 nm处有非常强的紫外峰。     

Luminescence of praseodymium (III) in solutions of mixed-ligand complexes with β-diketones

We have found that it is possible to enhance the luminescence of Pr(III) in solutions of complexes with β-diketones: acetylacetone derivatives containing fluoroalkyl substituents of different lengths and structures. We have established that in the presence of organic solvents, second (additional) ligands, and surfactants shielding the central ion from the quenching effect of the water molecules (OH oscillators), the intensity of luminescence for Pr(III) increases by a factor of 65, 38, and 45 respectively. In this case, cationic surfactants form ionic associates with Pr(III) β-diketonates, with incorporation of one more β-diketone molecule (ratio Pr:β-diketonate:surfactant = 1:4:1). As a result of suppression of intramolecular energy losses in solutions of Pr(III) β-diketonates, it is possible to observe its rather intense luminescence at 605 nm (the transition ¹D₂ → ³H₄), 612 nm (³P₀ → ³H₆), and 646 nm (³P₀ → 3F₂). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 746–750, November–December, 2006.     

Luminescence of CsBr:Eu films grown by liquid-phase epitaxy

By liquid-phase epitaxy from an aqueous alcoholic solution, we have obtained films of the well-known storage phospor CsBr:Eu, and we have studied their cathodoluminescence and photoluminescence (PL) spectra compared with the undoped CsBr films. We have established that the structure of the photoluminescence centers of the CsBr:Eu films when excited by laser radiation in the absorption band of the Eu²⁺ ions (λ = 337 nm) includes Eu²⁺-V_Cs isolated dipole centers and CsEuBr₃ aggregate centers, and also luminescence centers based on inclusions of hydroxyl group OH⁻ with the corresponding emission bands in the 440 nm, 520 nm, and 600 nm regions. We have studied the dependence of the spectra and the intensity of the photoluminescence for CsBr:Eu films on annealing temperature in air at 423–483 K, compared with analogous dependences for CsBr:Eu single crystals obtained from the melt. We have shown that annealing the films at T = 423–463 K leads to rapid formation of CsEuBr3 aggregate luminescence centers, while for T > 473 K thermal degradation of these centers occurs. We conclude that the observed differences between the photoluminescence spectra of CsBr:Eu films and CsBr:Eu single crystals may be due to additional doping of the films with OH⁻ ions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 191–194, March–April, 2006.     

Design of periodic metal-insulator-metal waveguide back structures for the enhancement of light absorption in thin-film solar cells

To increase the absorption in a thin layer of absorbing material (amorphous silicon, a-Si), a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enhance the optical path length of light within the solar cells. The new design can result in broadband optical absorption enhancement not only for transverse magnetic (TM)-polarized light, but also for transverse electric (TE)-polarized light. No plasmonic modes can be excited in TE-polarization, but because of the coupling into the a-Si planar waveguide guiding modes and the diffraction of light by the bottom periodic structures into higher diffraction orders, the total absorption in the active region is also increased. The results from rigorous coupled wave analysis show that the overall optical absorption in the active layer can be greatly enhanced by up to 40%. The designed structures presented in this paper can be integrated with back contact technology to potentially produce high-efficiency thin-film solar cell devices.     

稀土氟化物纳/微米材料的水热合成、形成机理和发光性质

研究了稀土氟化物纳/微米材料的设计合成、形貌控制、形成机制以及发光性质.发展了一种简单、整体、没有模板、环境友好的水热方法合成系列稀土氟化物,即用有机添加剂柠檬酸钠(Na3C6H5O7·2H2O)作为配位剂和形貌控制剂,通过改变氟源(NaF,NH4F或NaBF4)和最初溶液的pH值,得到了具有不同成分、晶体结构、尺寸和...