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Sadaharu Jo 《Applied Surface Science》2006,252(10):3514-3519
The morphologies and lattice structures of anthracene single crystals grown from the vapor phase were investigated using optical microscopy, phase contrast microscopy, atomic force microscopy (AFM), and X-ray diffraction analysis. Common morphologies with hexagonal large planes were observed irrespective of crystal size. The observation of certain surface morphologies with a phase contrast microscopy revealed that the spiral steps originated from screw dislocations present on the (0 0 1) planes. Moreover, the center and edge of the (0 0 1) planes had large curvatures, similar to hills. Resultantly, quarter-monolayer (ML) steps were observed on the large and flat planes between both hills. 相似文献
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A. Guillén-Cervantes Z. Rivera-ÁlvarezM. López-López A. Ponce-PedrazaC. Guarneros V.M. Sánchez-Reséndiz 《Applied Surface Science》2011,258(3):1267-1271
GaN thin films grown by MOCVD on (0 0 0 1) Al2O3 substrates at different growth pressures were characterized by field-emission scanning electron microscopy, atomic force microscopy, micro-Raman, and photoluminescence at room temperature. It was found that there is an optimum pressure of 76 Torr at which the structural and optical properties of the GaN samples are superior. On the other hand samples grown at higher pressure exhibited hexagonal surface pits and surface spirals. The results showed that the growth pressure strongly influences the morphology, and significantly affects the structural and optical properties of the GaN epilayers. 相似文献
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为了研究高功率系统中高反膜的损伤机制,对高功率系统中最常用的基频高反膜进行了损伤实验。利用台阶仪、扫描电镜、表面轮廓仪等手段,对实验样品的典型损伤形貌进行了比较和分析。结果表明:保护膜的存在增强了样品的抗激光损伤能力;未加保护膜样品的典型破坏形貌是由材料热物特性差异导致的分层剥落损伤,这类损伤在后续的脉冲辐照下会迅速发展;有保护膜样品的典型破坏形貌是中心带有μm量级小坑的等离子体烧蚀损伤区,其主要是由缺陷受热力作用喷溅导致,小坑附近膜面的凸起是这种力学作用的宏观体现,这类损伤在后续的脉冲辐照中表现得相对比较稳定。保护膜的存在,在一定程度上抑制了分层剥落这种灾难性损伤的出现,改善了样品的损伤特性。 相似文献
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Meriem Belhachemi Rachel V.R.A. Rios Fatima Addoun Joaquín Silvestre-Albero Antonio Sepúlveda-Escribano Francisco Rodríguez-Reinoso 《Journal of Analytical and Applied Pyrolysis》2009,86(1):168-172
Two series of activated carbons have been prepared from date pits; series C, using carbon dioxide as activating agent, and series S, prepared by activation with steam under the same experimental conditions. The obtained samples were oxidized with nitric acid in order to introduce more oxygen surface groups. The surface area and porosity of the parent and oxidized activated carbons were studied by N2 adsorption at 77 K and CO2 adsorption at 273 K. The oxygen surface complexes were characterized by temperature-programmed decomposition (TPD). The results show that carbon dioxide and steam activations produce microporous carbons with an increasing amount of CO evolving groups when increasing the burn-off. On the other hand, oxidation with nitric acid increases the amount of CO and CO2 evolved by the decomposition of surface oxygen groups, this increase being related to the development of porosity in the carbon with the degree of activation and to the activating agent used (CO2 versus steam). 相似文献
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Herein, we present a comparative analysis of a variety of chemical and physical fixation protocols for the specific visualisation of the membrane-bound vesicles (MBVs) in the Caco-2 colorectal cancer (CRC) cell line. In so doing, we validated the applicability of specific specimen preparation protocols for the preservation and contrasting of membrane-associated vesicles. Next, by employing the best respective chemical (GOT) and physical (SHPF) fixation methods for the application of transmission electron tomography and modelling we were able to characterise MBVs in three-dimensions and at the nanometer scale. In the second part of this study, we employ a correlative light and electron microscopy (CLEM) approach in order to determine which vesicular compartments are implicated in the uptake of FITC-BSA as a model protein drug. In so doing, we provide a solid foundation for future studies investigating chemotherapeutic drug uptake, transport and fate in cancer cell lines. 相似文献
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目前,中海油服已经建成了一批用于固井质量和套损检测的刻度井,刻度井群可以物理模拟不同的套管规格、水泥密度以及不同的水泥胶结状况等,可用于实现对固井质量和套损检测的声波测井仪器进行系统的标定和测试。以刻度井群中用于标定仪器在高密度和中密度水泥套管井中测量性能的应用为例,介绍了依据高精度的超声扫描、数值模拟和实际仪器的测试结果,初步实现对固井质量检测中常用的声幅-变密度测井(CBL/VDL)和扇区水泥胶结测井(SBT)仪器进行定量刻度和标定的步骤和方法。研究工作表明,质量测试可以掌握刻度井中各组成部分的声学物理参数以及胶结质量,在此基础上结合数值模拟和实际仪器的测量响应,可基本实现待测仪器工作性能的标定。 相似文献
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F. Zhao J. Ma B. Weng D. Li G. Bi A. Chen J. Xu Z. Shi 《Journal of Crystal Growth》2010,312(19):2695-2698
PbSe thin film was grown on a patterned Si substrate with (1 1 1)-orientation by molecular-beam epitaxy (MBE). On the mesa, a low dislocation density of 9×105 cm−2 was confirmed by the etch-pits density (EPD) wet-etching technique. The photoluminescence (PL) intensity at room temperature from the low dislocation PbSe film was much higher than that from the PbSe film grown on the planar area, which further indicated the high-quality of PbSe thin film grown on patterned Si substrate. 相似文献
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Kang-Shi Wang Roland Resch Kai Dunn Patrick Shuler Yongchun Tang Bruce E. Koel Teh Fu Yen 《Colloids and surfaces. A, Physicochemical and engineering aspects》1999,160(3):41-227
DTPA (diethylenetriaminepentaacetic acid) is a chelating agent widely used for removal of barium sulfate (barite) scale in the petroleum industry. In this paper we report ex-situ investigations of barite dissolution in deionized water and in 0.18 M DTPA aqueous solutions. Non-contact atomic force microscopy (NC-AFM) was used to observe dissolution on the BaSO4 (001) cleavage surface. Dissolution was carried out at room temperature in a 10 ml reactor. Each sample was first etched in solution and dried before examination by NC-AFM. Dissolution on the BaSO4 (001) surface took place via development of etch pits. In deionized water, triangular etch pits were observed on the (001) terraces at room temperature. And, zigzag shaped etch pits were found at the edges of steps. In DTPA solutions, etch pits on the (001) terraces were observed and these became deeper and longer with increasing time. The geometry of these etch pits was trapezoidal, and/or trapezohedral. To explain this characteristic morphology caused by dissolution we suggest that the active sites of one DTPA molecule bind to two or three Ba2+ cations exposed on the (001) surface. 相似文献
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Undoped and PbI2‐doped dendritic single crystals were grown by vapour growth technique. The basal surfaces of the as grown crystals were examined by optical and electron microscopy to observe wide variety of growth and defect features. Apart from typical features of dendritic growth, features of overgrowth, slip bands, growth steps and their bunching, etc. were observed. The basal surfaces of the crystals were then etched by controlled condensation of water vapour, after optimizing the etching condition, and the microscopic studies were repeated. Etch pits of hexagonal and triangular shape, both symmetric and asymmetric, and of different density, were observed in the case of undoped and doped crystals, respectively. In some cases, crystallographic hillocks were also observed. The crystals were also examined by X‐ray diffraction for their polytypism and related behaviour. The results are analyzed to elicit information on the correlation of structure, defects and surface features of the crystals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献