掺铒a-SixC1-x-H薄膜的发光特性

用等离子体增强化学气相沉积（PECVD）的方法，以固定的氢气（H2）流量和不同的硅烷（SiH4）和甲烷（CH4）流量比沉积了一系列的氢化非晶SiC（a-Si，C1-x-H）膜。用这种宽带隙的a-SixC1-x-H材料作为掺铒的基体材料，通过离子注入的方法得到掺铒的a-SixC1-x-H（a-SixC1-x-H：Er）膜。注入以后的样品经过不同温度的退火。用X射线光电子能谱（XPS）、红外吸收光谱（IR）、拉曼散射谱（Raman）等技术研究不同的SiH4／CH4流量比和退火温度对a-SixC1-x-H：Er发光强度的影响。结果表明，高温退火引起了膜中C的分凝，对饵的发光是不利的。通过低温和室温下铒发光强度的比较，表明这种材料具有较弱的温度猝灭效应。     

Origins of blinking in single-molecule Raman spectroscopy

We observe spectral and intensity fluctuations in Raman scattering from single molecules of 4-mercaptopyridine (4-Mpy) adsorbed on textured silver surfaces. We present evidence that the root cause of these fluctuations is thermal. Analysis of the spectra shows that in some cases the spectral changes are associated with molecular reorientation and in others with chemical reactions of the 4-Mpy. Analogous surfaces fully covered with 4-Mpy exhibit similar behavior, indicating that monolayer Raman spectra are dominated by a few molecules at most.     

Energy transfer from a polymer host to a europium complex in light-emitting diodes

Energy transfer leading to electroluminescence of a lanthanide complex, Eu(Fod)₃MK (Fod=heptafluoro-dimethyl-octanedionate, MK=4, 4′-bis(N,N-dimethylaminobenzophenone) doped into PVK host is investigated. The optical properties of pure Eu(Fod)₃MK and its doping in PVK show that the PVK host can efficiently transfer energy to europium ions through a co-ligand of MK due to good spectrally overlap. Light-emitting diodes (LED) consisting of PVK doped with 1-5 wt% of Eu(Fod)₃MK also demonstrates this energy transfer. Organolanthanide complexes doped into a wide-gap conducting polymers would lead to efficient and pure red organic LEDs to solve the full colour conjugated polymer displays.     

Determination of the exciton binding energy in single-walled carbon nanotubes

We report that measurements of the Raman intensity versus applied voltage are sensitive to filling of the density of states and enable us to measure the second band gap in specific semiconducting single-walled carbon nanotubes (SWNTs). Raman scattering preferentially selects sets of SWNTs whose excitonic transitions are resonant with the incident or scattered photon energies. Simultaneous measurement of the electronic gap and exciton resonance allows us to infer binding energies for the exciton of 0.49+/-0.05 and 0.62+/-0.05 eV for tubes of (10, 3) and (7, 5), respectively. Metallic SWNTs exhibit no excitonic feature.     

Surfactant-Mediated Ultrasonic-Assisted Extraction and Purification of Antioxidants from Chaenomeles speciosa (Sweet) Nakai for Chemical- and Cell-Based Antioxidant Capacity Evaluation

In this study, a surfactant-mediated ultrasonic-assisted process was used for the first time to produce an antioxidant-enriched extract from Chaenomeles speciosa (Sweet) Nakai (C. speciosa, a popular fruit grown widely in the temperate regions of China). Ultrasonic treatment at 51 °C and 200 W for 30 min with sodium dodecyl sulfate as the surfactant led to a phenolic yield of 32.42 mg/g from dried C. speciosa powder, based on single-factor experiments, the Plackett–Burman design and the Box–Behnken design. The phenolic content increased from 6.5% (the crude extract) to 57% (the purified extract) after the purification, using LSA-900C macroporous resin. Both the crude and purified extracts exhibited a significant total reducing power and DPPH/ABTS scavenging abilities, with the purified extract being more potent. The purified extract exerted significant antioxidant actions in the tert-butyl hydroperoxide-stimulated HepG2 cells, e.g., increasing the activities of superoxide dismutase and catalase, while decreasing the reactive oxygen species and malondialdehyde levels, through the regulation of the genes and proteins of the Nrf2/Keap1 signaling pathway. Therefore, the extract from C. speciosa is a desirable antioxidant agent for the oxidative damage of the body to meet the rising demand for natural therapeutics.     

X射线辐照后BaFC1中缺陷性质的研究

未掺Eu~(2+)的BaFCl粉末样品在80K下经X射线辐照后,在不同的温度条件下(从80K副273K),用580nm的光波激励样品时观测到310nm和380nm的发光峰.经分析认为,样品经X射线辐照后,在晶体中形成两种卤素离子的F-H’心对.当用F心吸收带的光波激励样品时,两种F—H心对衰变成相应的自陷激子态并复合发光.310nm和380nm分别对应于F-离子和Cl-离子的自陷激子的发光,并且它们的发光强度强烈地依赖于温度的变化。     

温度对半胱氨酸缓蚀性能影晌的实验评价与机理研究

通过实验对不同温度条件下半胱氦酸抑制盐酸对碳钢腐蚀的性能进行评价,并采用分子动力学模拟(Molecular Dynamics Simulation,简称MD)方法,从缓蚀剂膜抑制腐蚀粒子扩散的角度对其缓蚀机理进行深入研究.静态失重实验显示:随温度的升高(25～65℃),半胱氨睃缓蚀剂的缓蚀效率呈逐渐下降趋势,其数值从88.36%降至61.64%.MD模拟发现:随温度升高,半胱氨酸缓蚀剂膜的自由体积逐渐增大,且腐蚀粒子与缓蚀剂膜的相互作用也逐渐减弱,更有利于腐蚀粒子在膜中的主动扩散;同时膜内半胱氨酸分子的自扩散能力也随温度升高而增强,腐蚀粒子在缓蚀剂膜携带下被动迁移的过程也随之加剧.主动扩散和被动迁移两方面的变化表明,腐蚀粒子在缓蚀剂膜中扩散能力随温度升高而增大;也就是说,随温度升高,半胱氨酸缓蚀剂膜对腐蚀粒子的扩散抑制能力逐渐降低,腐蚀粒子更易扩散运移至金属表面,导致半胱氨酸缓蚀剂缓蚀效率的降低.     

Enhancement of adsorbed dye monolayer fluorescence by a silver nanoparticle overlayer

Deposition of silver nanoparticles directly onto a Rhodamine Red monolayer covalently bound to glass is found to increase the photoluminescence by as much as 20 times depending on excitation wavelength and nanoparticle density. At the same time, the excited state lifetime is reduced by more than a factor of 2, the fluorescence spectrum is blue-shifted, and greater polarization anisotropy in the emission is observed. We attribute these effects to local enhancement of the optical fields near the molecules by interactions with silver plasmons. We approximately separate the relative contributions of increased absorption and increased emissive rate to the observed enhancement of fluorescence. A study of the spatial inhomogeneity of the effect using scanning confocal microscopy demonstrates that average enhancements at least twice as large are possible.     

气相色谱法分析食用蟹味油

method for analysis of the edible oil with crab taste by gas chromatography has been developed. The sample was directly introduced on a Silicone XE-60 capillary column . 25m×0. 25mm×0. 5μm, with a one-ramp temperature programming (hold 10min at 80℃, increased upto 180℃ at 20℃/min and then hold 20min) and detected by FID. For the component identification mass spectrometry was used. The above condition was chosen after in comparison with a PEG-20M column.