Covalent dyads of porphyrin-fullerene and perylene-fullerene for organic photovoltaics: Spectroscopic and photocurrent studies

Supermolecular complexes of zinc porphyrin or perylenediimide as covalent dyads with fullerene (C₆₀) in chloroform and as Langmuir-Blodgett layers on an Au substrate were studied. In our studies we have used following spectroscopic methods: electronic absorption, fluorescence and electron spin resonance in solution. Also infrared absorption spectra in a KBr pellet and reflectance-absorption in Langmuir-Blodgett layers were monitored. Photocurrent generation in a photoelectrochemical cell was also studied. The redistribution of charge both upon porphyrin linkage to C₆₀ and when the systems are deposited on the Au substrate was shown. Photocurrent examinations show a great influence of the fullerene presence on photoresponse of the systems.     

Interstellar Polycyclic Aromatic Compounds and Astrophysics

Over the past 15 years, thanks to significant, parallel advancements in observational, experimental, and theoretical techniques, tremendous strides have been made in our understanding of the role polycyclic aromatic compounds (PACs) in the interstellar medium (ISM). Twenty years ago, the notion of an abundant population of large, carbon-rich molecules in the ISM was considered preposterous. Today, the unmistakable spectroscopic signatures of PACs--shockingly large molecules by previous interstellar chemistry standards--are recognized throughout the universe. In this article, we will examine the interstellar PAC model and its importance to astrophysics, including: (a) the evidence which led to inception of the model, (b) the ensuing laboratory and theoretical studies of the fundamental spectroscopic properties of PAC by which the model has been refined and extended, and (c) a few examples of how the model is being exploited to derive insight into the nature of the interstellar PAC population.     

不同温度条件下铬酸盐钝化镀锡板的耐蚀性研究

以镀锡钢板钝化工艺中的钝化温度为研究对象,使用金相观察、X射线光电子能谱(XPS)、电化学等试验方法,讨论了不同温度条件对铬酸盐钝化镀锡板的耐中性溶液腐蚀、耐硫蚀、耐酸蚀等性能的影响以及钝化膜表面元素铬的元素价态.结果表明:铬元素在钝化膜中的状态为2种铬的化合物组成,分别为Cr2O3和Cr(OH)3.随着钝化温度的增加,钝化镀锡板耐中性溶液腐蚀有不同程度的增强,镀锡板耐硫蚀以及耐酸蚀性能均提高.     

Vibrational spectroscopic characterization of rigid rod polymers: 3. Microstructural changes in stressed polymers

Highly oriented poly(p-phenylene benzobisthiazole) films were stressed in a miniature hydraulic tensile tester interfaced to a fast scanning Fourier transform infra-red spectrometer. The changes in relative intensity, polarization, frequency and shape of infrared bands have been useful in the elucidation of microstructures. With the short time resolution achievable, vibrational bandshape and frequency have been shown to change at different rates when an external stress was applied.     

tau: A 1D radiative transfer code for transmission spectroscopy of extrasolar planet atmospheres

The tau code is a 1D line-by-line radiative transfer code, which is generally applicable for modeling transmission spectra of close-in extrasolar planets. The inputs are the assumed temperature–pressure profile of the planetary atmosphere, the continuum absorption coefficients and the absorption cross-sections for the trace molecular absorbers present in the model, as well as the fundamental system parameters taken from the published literature. The program then calculates the optical path through the planetary atmosphere of the radiation from the host star, and quantifies the absorption due to the modeled composition in a transmission spectrum of transit depth as a function of wavelength. The code is written in C++, parallelized using OpenMP, and is available for public download and use from http://www.ucl.ac.uk/exoplanets/.     

Use of a Reflectance Spectroscopy Accessory for Optical Characterization of ZnO-Bi(2)O(3)-TiO(2) Ceramics

The optical band-gap energy (E(g)) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. E(g) of the ceramic ZnO + xBi(2)O(3) + xTiO(2), where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. E(g) was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.     

三聚氰胺分子印迹聚合物的合成与光谱学特性

采用非共价印迹法,以三聚氰胺为模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,合成了三聚氰胺分子印迹聚合物．实验表明该印迹聚合物对甲醇溶液中三聚氰胺具有良好的选择性结合能力,对液态奶中的三聚氰胺的富集率可达98％以上．并结合紫外光谱及红外光谱对分子印迹聚合物的合成及结合机理进行了初步解析．     

The role of Al in C-S-H: NMR, XRD, and compositional results for precipitated samples

X-ray diffraction, compositional analysis, and ²⁹Si and ²⁷Al MAS NMR spectroscopy of Al-substituted tobermorite-type C-S-H made by precipitation from solution provide significant new insight into the structural mechanisms of Al-substitution in this important and complicated phase. Al occurs in 4-, 5-, and 6-coordination (Al[4], Al[5], and Al[6]) and plays multiple structural roles. Al[4] occurs on the bridging tetrahedra of the drierkette Al-silicate chains, and Al[5] and Al[6] occur in the interlayer and perhaps on particle surfaces. Al does not enter either the central Ca-O sheet or the pairing tetrahedra of the tobermorite-type layers. Al[4] occurs on three types of bridging sites, Q³ sites that bridge across the interlayer; Q² sites that are charge balanced by interlayer Ca⁺², Na⁺, or H⁺; and Q² sites that are most likely charge balanced by interlayer or surface Al[5] and Al[6] through Al[4]-O-Al[5,6] linkages. Although the data presented here are for relatively well-crystallized tobermorite-type C-S-H with C/S ratios ≤ 1.2, comparable spectral features for hydrated white cement pastes in previously published papers[30], [31] and [32] [M.D. Andersen, H.J. Jakobsen, J. Skibsted, Incorporation of aluminum in the calcium silicate hydrate (C-S-H) of hydrated Portland cements: a high-field ²⁷Al and ²⁹Si MAS NMR investigation Inorg. Chem. 42 (2003) 2280-2287; M.D. Andersen, H.J. Jakobsen, J. Skibsted, Characterization of white Portland cement hydration and the C-S-H structure in the presence of sodium aliminate by ²⁷Al and ²⁹Si MAS NMR spectroscopy, Cem. Concr. Res. 43 (2004) 857-868; M.D. Andersen, H. J. Jakobsen, J. Skibsted, A new aluminum-hydrate phase in hydrated Portland cements characterized by ²⁷Al and ²⁹Si MAS NMR spectroscopy, Cem. Concr. Res., submitted for publication.] indicate the presence of similar structural environments in the C-S-H of such pastes, and by implication OPC pastes.     

应用于早期火灾探测的CO传感器

为了实现对火灾的早期探测,设计了一种高精度、高灵敏度CO传感器。该传感器以激射波长的为2.33μm的连续型分布反馈激光器为光源。采用波长调制光谱(WMS)技术与一次谐波量化的二次谐波检测方法相结合的研究手段,对典型环境压力下复杂、重叠的光谱吸收特征进行分离,从而实现了良好的选择性和较高的灵敏度。基于Allan Werle方差的系统长期稳定性评估分析表明,系统的检测限(LoD)为1.18μL/L;当积分时间达到205s时,系统能够实现0.08μL/L的测量精度。最后,纸、棉花以及松木等容易产生阴燃的可燃物燃烧实验表明,所研制的传感器具有良好的早期火灾探测能力。     

近红外光谱分析技术及发展前景

本文介绍了近红外光谱分析技术的发展简史、工作原理、技术特点、基本分类、仪器结构及典型用途及发展前景。