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Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) has been used to perform a chemical analysis of long‐chain thiol (CH3(CH2)11SH)‐treated gold, silver, copper and platinum surfaces. All the mass peaks from positive and negative ion spectra within the range m/z = 0–2000 u are studied. ToF‐SIMS data revealed that on gold, silver and copper substrates 1‐dodecanethiol form dense standing‐up phases, but on platinum being a catalytically active substrate, we were able to identify also surface‐aligned parallel lying molecules in addition to a standing thiolate layer. Our study shows that when ToF‐SIMS spectra are analyzed, not only the existence of oligomers but also metal + hydrocarbon fragments give information about the order of SAM. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Lauri Järvinen Jarkko Leiro Frej Bjondahl Claudio Carletti Tom Lundin Kristian Gunnelius Jan‐Henrik Smått Olav Eklund 《Surface and interface analysis : SIA》2015,47(2):284-294
The aim of this study was to compare different types of dolomites through batch reactivity experiments between HCl and dolomite powders, and ex‐situ characterisation of the particles before and after dissolution. Sedimentary dolomites were observed to have higher initial reactivities than metamorphic ones with sufficiently low calcite concentrations (<6% according to our regression model). In addition, the initial reactivities of the metamorphic dolomites were dependent on calcite concentration and could exceed those of the sedimentary dolomites. A regression model is presented for the dependence of initial reactivity on mineral composition and type of origin (sedimentary/metamorphic). The samples with the highest initial reactivities had also the largest BET (Brunauer, Emmet, Teller) surface areas obtained with nitrogen physisorption. Yet our data indicates that mineral composition of the dolomite has a greater influence on the initial reactivity than the BET surface area. Furthermore, it was found that the surface of sedimentary dolomites, unlike the surface of metamorphic dolomites, becomes porous during dissolution. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Background
It is well known that both semantic and syntactic information play a role in pronoun resolution in sentences. However, it is unclear what the relative contribution of these sources of information is for the establishment of a coreferential relationship between the pronoun and the antecedent in combination with a local structural case constraint on the pronoun (i.e. case assignment of a pronoun under preposition governing). In a prepositional phrase in German and Dutch, it is the preposition that assigns case to the pronoun. Furthermore, in these languages different overtly case-marked pronouns are used to refer to male and female persons. Thus, one can manipulate biological/syntactic gender features separately from case marking features. 相似文献54.
The self-assembled monolayers prepared from 1-dodecanethiol (C12SH) or S-dodecylthiosulfate (Bunte salt, C12SSO3Na) have been characterised on polycrystalline gold and platinum surfaces and on Pt(1 1 1). Contact angle and impedance measurements show that the film quality decreases in the order Au/C12SH > Pt/C12SH ∼ Au/C12SSO3Na > Pt/C12S SO3Na. XPS measurements show that the S-SO3 bond of organic thiosulfates is broken on platinum surfaces and the state of the surface-bound sulfur is indistinguishable from that of thiolate. On platinum three sulfur species are formed upon SAM formation and we suggest that the catalytic activity of platinum is responsible for their existence in pristine monolayers. 相似文献
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Microwave heating of ceramic composites 总被引:1,自引:0,他引:1
The microwave heating of a ceramic composite is modelled andanalysed. The composite consists of many small ceramic particlesembedded in a ceramic cement. The composite is assumed to bewell insulated, and each particle is assumed to be in imperfectthermal contact with the surrounding cement. Based on thesetwo assumptions an asymptotic theory exploiting the small Biotnumber and small non-dimensional contact conductance is developed.Our asymptotic theory yields a set of nonlinear partial differentialequations which govern the temperature in the composite. Theseare reduced to a set of coupled nonlinear ordinary differentialequations in which the surface area of each particle entersas a parameter. Recent experiments with such composites haveshown that the steady-state temperature of the composite isstrongly dependent upon the radii of the embedded particles.Our model captures this effect. In fact, our analysis showsthat the assumption of imperfect thermal contact between theparticles and the ceramic cement is essential for this trendto be established. 相似文献
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The surface core-level shift and surface segregation of a Pd93Rh7 alloy have been considered in the light of X-ray photoemission spectroscopy. A core-level shift of the Pd3d line to a lower binding energy as far as the surface atoms are concerned has been observed, which can be expected on the basis of the Z + 1 approximation. Also, surface segregation of Pd atoms has been found by using different take-off angles between the momentum of the escaping photoelectron and the surface of the Pd---Rh alloy. This effect has been discussed in terms of the surface density of electronic states and the d-band occupancy of an alloy. 相似文献
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ICP-AES法测定色漆可溶性金属含量 总被引:1,自引:0,他引:1
用ICP-AES法测定了色漆中的“可溶性”金属铬、镉、铅元素,考察了不同酸度对分析结果的影响,优化了测试条件。进行了回收率和精密度试验。并用原子吸收光谱国标方法进行对照,结果一致。 相似文献
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