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121.
Amorphous dihalonaphthalenes that are prepared by vacuum deposition onto a cold Al2O3 surface form electronically excited dimers when optically pumped, and their emission is characteristically red-shifted, broad and featureless compared to the monomeric fluorescence. If the surface is heated, the adlayer undergoes a disorder-to-order transition at a temperature characteristic of the molecule. Since pure crystalline dihalonaphthalenes typically fluoresce and do not exhibit excimeric features, the transition was studied by taking advantage of the changes in the spectral characteristics of the adlayer. These included transmittance, and emission from fluorescence and excimer. The combination of these methods allowed a close look at the surface dynamics of molecules on the surface of Al2O3 as the adlayer was heated from the deposition temperature to desorption.If a bilayer is formed by depositing water onto the surface with the organic adlayer on top, water, with its lower desorption energy, can be made to percolate into the organic layer. The optical probes indicate that the water clearly associates with the organic molecules while the excess water desorbs. By varying the coverage of either the water or the dihalonaphthalene, the stoichiometric composition of the cluster can be determined and are reported here. 相似文献
122.
Lithium niobate thin films have been deposited on Pt/Ti/SiO2/Si(100) substrates by Pechini method. Characterization of the initial precursor solutions containing citric acid (CA), niobium and lithium ions has been performed by Fourier transform infrared spectroscopy, Raman spectroscopy and carbon nuclear magnetic resonance spectroscopy. The results indicate that citric acid coordinate to niobium ions to form a niobium-CA complex through one terminal carboxyl group, the hydroxyl group and the central carboxyl group as a tridentate ligand. The thermal decomposition of the Li-Nb precursors gel powder has been studied and the results show that LiNbO3 phase is formed directly from the thermal decomposition of the precursor gel. By heat-treatment at 600 °C for 2 h, polycrystalline LiNbO3 thin films with smooth and crack-free surface could be achieved. 相似文献
123.
Commercially available carbon-based thin films consisting of single layers of amorphous diamond-like carbon or multilayers of crystalline TiAlN or CrN with diamond-like carbon top coatings were evaluated in relation to their electrochemical corrosion behavior in chloride ions containing electrolytes. The hardened working steel (an alloy of 0.9% C, 4.1% Cr, 4.9% Mo, 1.8% V, 6.4% W) was used as a substrate material.The potentiodynamic corrosion behavior of coated samples was tested in 3.5 wt.% NaCl solution and Hank's balanced body solution, HBBS (0.89 wt.% NaCl, further chlorides, sulfates, carbonates and phosphates). The multi-layers TiAlN + a-C:H:W and CrN + a-C:H:W exhibited only a minor improvement in corrosion resistance. Single layers of amorphous diamond-like carbon coating without hydrogen (a-C) spall off during the corrosion tests in chloride containing media. A minor improvement of the corrosion resistance is possible. The a-C:H and the a-C:H:Si, which contain hydrogen, showed the best corrosion resistance with a 100 times lower corrosion current density. 相似文献
124.
Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials. 相似文献
125.
利用发射光谱(Optical emission spectroscopy,OES)对感应耦合等离子体增强化学气相沉积(Inductivelycoupled plasma enhance chemical vapor d印osition,ICPECVD)类金刚石(Diamondlike carbon,DLC)膜过程中的各种基团进行分析,并对不同条件下薄膜沉积速率以及薄膜显微硬度进行测试.分析结果发现,感应耦合等离子体源激发甲烷等离子体中存在比较突出的碳氢离子成分,从而促进形成高硬度的DLC膜.而且射频功率、沉积气压等沉积参数的变化对DLC薄膜沉积过程的中性基团、离子基团以及原子氢等成分都有着明显影响,从而最终影响薄膜沉积过程及薄膜性质. 相似文献
126.
127.
L. Pasquali S. Nannarone 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,230(1-4):340-350
A review is given of the application of metastable deexcitation spectroscopy (MDS) to the study of the interface formation between semiconductors and different materials. In particular we present an overview of the results obtained on nanostructured interfaces, where strain and reaction between the substrate and the overlayer atoms drive the growth mode and the morphology of the system. As prototypical examples we discuss the growth of CaF2 on silicon and rare earths (Yb, Er) on silicon and gallium arsenide. The mechanisms and chemical reactions which bring to interface formation are examined on the basis of MDS results and their comparison with photoemission. 相似文献
128.
陈华才 《中国计量学院学报》2005,16(4):299-301
利用傅立叶变换红外光谱仪直接采集PE和PVC食品保鲜膜的红外投射光谱,比较了两种食品保鲜膜的红外光谱特征,明确了各自主要特征峰的归属.通过检索标准谱库与标准谱图进行对照,对两种保鲜膜进行了定性鉴定.该方法不需要任何样品前处理过程,具有快速、方便、准确的优点,是对市场上两种食品保鲜膜进行快速定性鉴别的理想方法之一. 相似文献
129.
Correlation between ionic conductivity and fluidity of polymer gel electrolytes containing NH4CF3SO3
Nonaqueous polymer gel electrolytes containing ammonium triflate (NH4CF3SO3) and dimethylacetamide (DMA) with polymethylmethacrylate (PMMA) as the gelling polymer have been synthesized which show high
value of conductivity (~ 10-2 S/cm) at 25°C. The conductivity of polymer gel electrolytes containing different concentrations of NH4CF3SO3 shows a small decrease with the addition of PMMA and this has been correlated with the variation of fluidity of these gel
electrolytes. The small decrease in conductivity with PMMA addition shows that polymer plays the role of stiffener and this
is supported by FTIR results which also indicates the absence of any active interaction between polymer and NH4CF3SO3 in these gel electrolytes. 相似文献
130.
In this article, particle size distributions (PSDs) measured by different techniques, including image analysis (IA), laser diffraction (LD), ultrasonic attenuation spectroscopy (UAS), and focused-beam reflectance measurement (FBRM), are compared for spherical glass beads and nonspherical silica flakes. It is shown that particle shape strongly affects the results obtained by different techniques. For spheres, the PSDs obtained by IA, LD, and UAS agree well. There is no consistent result among different particle measurement techniques for nonspherical particles. The conversion between PSDs obtained by IA, LD, and UAS has been based on particle shape factors. Caution must be exercised when a measured chord length distribution (CLD) is used to indicate the PSD during a process because the CLD result obtained by FBRM is complex, depending not only on the PSD, but also on particle optical properties and shape. 相似文献