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101.
Kuniharu Fujii Satoshi Kera Mika Oiwa Koji K. Okudaira Kazuyuki Sakamoto Nobuo Ueno 《Surface science》2007,601(18):3765-3768
We have investigated the relation between the intramolecular vibrational modes of pentacene and the charge redistribution at the pentacene-graphite interface by using high-resolution electron-energy-loss-spectroscopy. The three main vibrational peaks shift to lower energies as the pentacene film thickness decreases. In order to discuss this energy shift, we have calculated the vibrational energies of a free pentacene molecule by changing its charge state. We have also calculated the vibrational energies of a pentacene molecule adsorbed on a graphite sheet by changing the pentacene-graphite distance. Taking the experimental and calculation results into account, we conclude that the observed energy shifts result from an intramolecular charge redistribution. The present results indicate that the effect of an intramolecular charge redistribution is essential to discuss the origin of an energy shift observed in a vibrational study of an organic molecule/substrate interface. 相似文献
102.
石墨炉原子吸收光谱法测定血铅的干扰校正 总被引:3,自引:0,他引:3
研究了用石墨炉原子吸收光谱法测定血铅的干扰校正方法。通过对测定过程中的干扰研究,建立了一种数学校正干扰的标准加入法基体匹配工作曲线。用本法分析健康儿童血铅及脐带血铅,线性范围为0 ̄90ng/L,相关系数为0.9997,灵敏度为8.6pg/1%信号,检出限为4.8pg,与一般标准加入法工作曲线相比较,测定血铅线性斜率大,灵敏度高,准确性好。 相似文献
103.
石墨炉原子吸收法测定芦笋罐头中砷 总被引:3,自引:0,他引:3
采用石墨炉原于吸收法测定芦笋罐头中砷,加入硝酸铵消除氯化钠的干扰,并以镍作为基体改进剂,方法检出限为0,10μkg-1,特征量为0.80pg,回收申为94%一1。5%。 相似文献
104.
Abstract Scanning probe microscopy experiments show that ion irradiation of (0001) graphite results in the formation of isolated defects comprising of a few tens of atoms. We use molecular dynamics simulations and density-functional theory calculations to study the formation probabilities of these defects. We identify different defect structures which correspond to experimentally observed hillocks on graphite surfaces. We find that the predominant source of defects are vacancies and interlayer interstitials, and identify a three-atom carbon ring defect on the graphite surface. 相似文献
105.
106.
The first steps of structural and electronic modifications of a graphite surface bombarded with argon, hydrogen and deuterium ions were investigated using high resolution electron energy loss spectroscopy (HREELS). The energy and the damping of the low energy plasmon mode of graphite (E//C mode) were studied with respect to the bombardment settings. We show that argon bombardment affects the energy of the plasmon mode, while no similar change is observed after hydrogen (deuterium) bombardments. This can be related to the variation of inter-planar distance between two graphene layers. Moreover, the damping of the plasmon mode can be correlated with the interstitial defect concentration. Concerning the reactivity of the bombarded surfaces, we demonstrate that deuterium bombardment produce a non-deuterated surface. This last is very reactive to a further atomic deuterium exposure, as it is shown by the formation of C-D bondings. The deuterated sites can be removed after thermal annealings between 473 and 783 K. The occurrence of a chemical erosion mechanism accompanying this deuteration is discussed. 相似文献
107.
Isabel C.F. Damin Morgana B. Dessuy Tamara S. Castilhos Márcia M. Silva Maria Goreti R. Vale Bernhard Welz Dmitri A. Katskov 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
The determination of trace elements in crude oil is difficult due to the complex nature of the sample and the various different chemical forms in which the metals can occur. The advantage of graphite furnace atomic absorption spectrometry is that only a minimum of sample pretreatment is required. In this work two techniques have been compared to establish a fast and reliable method for lead determination in crude oil. In the first one the crude oil samples were weighed directly onto solid sampling (SS) platforms and introduced into the graphite tube for analysis. In the second one the samples were prepared as oil-in-water emulsions and analyzed in a filter furnace (FF). Twenty μL of a mixture of 0.5 mg L− 1 Pd + 0.3 mg L− 1 Mg + Triton X-100 has been used as the modifier, and calibration against aqueous solutions has been used for both methods. The sensitivity obtained with the FF was more than a factor of two better than that with SS; however, as a larger sample mass could be introduced in the latter case, so that the limits of detection for both techniques were 0.004 mg kg− 1. Seven crude oil samples were analyzed using the two procedures, and all results were in agreement at a 95% confidence level using a paired Student's t-test. For validation purposes, three crude oil samples have been mineralized using an open-vessel acid digestion, and the results were in agreement with those found with direct sampling and with emulsion sampling using FF according to ANOVA test. Both methods are simple, fast and reliable, being appropriated for routine analysis; however, the direct method using SS technology should be preferred because of its simplicity, speed and commercial availability. 相似文献
108.
To improve the cycling performance of graphite anode materials, we propose a functional electrolyte additive, trimethoxymethylsilane (TMSi), which contains a silyl ether functional group as part of its molecular structure. First principal calculation studies, in addition to ex situ analyses, demonstrated that electrochemical reduction of ethylene carbonate (EC) gives an anionic reduced EC product. Subsequent chemical reaction with TMSi then generates solid-electrolyte interphase (SEI) layers of Si–O and Si–C functionalized carbonate on the surface of the graphite anode, which prolongs and stabilizes the cycling performance of the cells. As a result, the cell cycled with TMSi-controlled electrolyte exhibits a cycling retention of 89.5%, whereas the cell cycled with standard electrolyte suffers from poor cycling retention (84.3%) after 100 cycles. 相似文献
109.
Jagdeep S. Sagu K.G. Upul Wijayantha Paul Holland Mallika Bohm Siva Bohm Tapan Kumar Rout Hemaka Bandulasena 《Crystal Research and Technology》2016,51(8):466-474
Carbon emissions from industrial sources are of major global concern, especially contributions from the steel manufacturing process which accounts for the majority of emissions. Typical blast furnace gases consist of CO2 (20‐25%), CO (20‐25%), H2 (3‐5%) and N2 (40‐50%) and trace amounts of other gases. It is demonstrated that gas mixtures with these compositions can be used at atmospheric pressure to grow carbon nanotubes (CNTs) by chemical vapor deposition (CVD) on to steel substrates, which act as catalysts for CNT growth. Computational modelling was used to investigate the CNT growth conditions inside the CVD chamber. The results show that industrial waste pollutant gases can be used to manufacture materials with significant commercial value, in this case CNTs. 相似文献
110.
Izzet Koçak 《Analytical letters》2017,50(9):1448-1462
1-(N-Boc-aminomethyl)-4-(aminomethyl)benzene, bearing a protected amine group, was electrochemically grafted to glassy carbon and edge plane and basal plane highly oriented pyrolytic graphite electrodes by the oxidation of the corresponding linker. Following the removal of tert-butyloxycarbonyl protecting group, anthraquinone-2-carboxylic acid was coupled to the amine-terminated linker using solid-phase synthesis. The surface coverage of the immobilized anthraquinone redox centers was investigated by cyclic voltammetry and found to be the highest at edge plane and the lowest at the basal plane electrodes. The electrocatalytic activity of the anthraquinone-modified electrodes toward oxygen reduction was explored by cyclic voltammetry, chronoamperometry, and chronocoulometry at the unmodified and modified graphite electrodes. The immobilized anthraquinone was shown to catalyze the reduction of oxygen to hydrogen peroxide and the number of electrons transferred was two for all modified electrodes. 相似文献