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07ACS-National Meeting论文Abstract_Inorganic(有Nano的)
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INOR 21 Synthesis and characterization of covalently attached polyethyleneimine functionalized single-wall carbon nanotubes Christopher A. Crouse, Eoghan Dillon, Ramon Colorado Jr., and Andrew R. Barron, Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX 77005, crous1ca@rice.edu The solubility of single-wall carbon nanotubes (SWNTs) in aqueous and organic solvents is a difficult barrier that must be overcome to allow for potential applications in the biomedical and material sciences. Previous work involving the addition of polymers towards the dissolution of SWNTs has focused on the covalent attachment of polymers to the carboxylic acid moieties found at the open ends of SWNTs or the physical adsorption of polymers or surfactants on the sidewalls. In this work the reaction between branched-polyethyleneimine (PEI) and uncut, fluorinated-SWNTs (F-SWNTs) was performed yielding the covalent attachment of the polymer to the sidewalls of the nanotubes. These results were confirmed through solid state NMR, Raman spectroscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy and thermal gravimetric analysis studies. The resulting PEI functionalized SWNTs (PEI-SWNTs) are shown to have an increased solubility in aqueous media of up to 0.4 mg/mL. The synthesis, characterization, and possible biomedical applications of the newly formed PEI-SWNTs will be discussed. INOR 22 Synthesis of aligned single-walled carbon nanotube networks Chris Papadopoulos and Badr Omrane, Department of Electrical and Computer Engineering, University of Victoria, Victoria, BC V8W 3P6, Canada, papadop@uvic.ca With their excellent combination of mechanical, thermal, chemical and electrical properties, single-walled carbon nanotubes (SWNTs) have emerged as one of the most important materials in nanoscale science and technology. However, the controlled synthesis of SWNTs remains a key challenge for their practical implementation. In particular, controlling the type, size, positioning and orientation of nanotubes will be crucial for translating their fundamental properties into useful structures. Here we employ catalytic chemical vapor deposition coupled with precise nanoscale patterning to promote the alignment of lateral SWNT networks grown on silicon wafers. Results of growth trials and characterization of the networks via electron microscopy and scanning probe methods will be presented. The electronic properties and potential applications of the aligned SWNT networks will also be discussed. INOR 23 Substrate effects on the growth of single-walled carbon nanotubes (SWNTs) from iron complexes, clusters, and colloids on surfaces Ramon Colorado Jr., Christopher A. Crouse, Clayton C. Gallaway, Alvin Orbaek, and Andrew R. Barron, Department of Chemistry, Smalley Institute for Nanoscale Science and Technology, Rice University, 6100 Main Street, Houston, TX 77005, colorado@rice.edu Our investigations of the vapor-solid-liquid (VLS) growth of single-walled carbon nanotubes (SWNTs) from metallic catalysts on solid substrates (e.g. iron nanoparticles on silicon wafers) have suggested that there is a correlation between the nature of the substrate and the activity of the growth catalyst. An understanding of potential catalyst activation and deactivation pathways is essential in developing methods for increasing the total yield of grown SWNTs from catalyst precursors. To this end, we have studied the VLS growth of SWNTs from iron oxide catalyst precursors on various substrates (Si, Spin-on-glass, HOPG, Al2O3) under different growth conditions (i.e. varying growth temperatures and gases). In addition, we have examined how changes in the roughness and morphology of the substrates affect nanotube growth with respect to both the catalyst activity and the orientation of the grown nanotubes. Characterization of the SWNTs by AFM, SEM, and Raman spectroscopy will be presented. INOR 26 Synthesis of small diameter carbon nanotubes by catalytic decomposition of methane Xiang-ju Xu and Shao-ming Huang, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China, daisyxxj2003@yahoo.com.cn Small diameter carbon nanotubes(CNTs) have been synthesized over Fe/Mo/MgO catalyst by catalytic decomposition of methane at 1000°C. The produced carbon material primarily consists of a CNTs bundle with a small amount of individual CNTs. The diameter of an individual CNTs is in the range of 5-10 nm. The as-synthesized CNTs have a yield of over 100% relative to the weight of supplied catalyst. Critical issues for synthesis of small diameter CNTs were further discussed in terms of procedure of catalyst preparation, growth time, and temperature. Our results show that methane can be a very ideal carbon source for the synthesis of small diameter CNTs. We suggest that catalytic decomposition of methane over Fe/Mo/MgO catalyst can promise a large-scale production of small diameter CNTs. INOR 27 “Green” approach for fabrication of conducting polymer nanocomposite: The catalytic role of carbon nanotubes Yufeng Ma, Pui Lam Chiu, Arnaldo Serrano, Alex Chen, and Huixin He, Chemistry Department, Rutgers University, 73 Warren Street, Newark, NJ 07102, Fax: 973-353-1264, huixinhe@newark.rutgers.edu The catalytic behavior of carbon nanotubes (CNTs) just aroused a hot debate. For a long time people believed that the electrocatalytic properties of CNTs can be exploited for a wide variety of applications. However, very recently, Compton and coworkers challenged these general beliefs and demonstrated that the origin of the electrocatalytic behavior of CNTs observed previously is the metal catalyst residues, such as iron oxide particles, that remain in the batch after the fabrication of nanotube and the purification process. In this report, we will present the intrinsic catalytic capability of the single-walled carbon nanotubes (SWNTs). This catalytic capability is not only chirally selective, but also depends on the dispersion methods and dispersion agents used to disperse them into aqueous solutions. Due to the remarkable catalytic capability of the SWNTs, conducting polymer nanocomposites are fabricated by a “greener” process. INOR 28 Photocatalytic nanofibers and nanotubes made by atomic layer deposition Markku Leskela, Marianna Kemell, Viljami Pore, Eero Santala, and Mikko Ritala, Department of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FIN-00014, Finland, Fax: +358 9 191 50198, markku.leskela@helsinki.fi Because of the self-limiting growth principle Atomic Layer Deposition (ALD) suits very well for depositing thin films on nonplanar surfaces. Neither the size of the substrates nor the size of the structural features has any clear threshold value in ALD. ALD suits very well for making and modifying of nanomaterials. In this presentation the use of ALD for depositing conformal TiO2 films on nonplanar nanostructured surfaces is exemplified by three ways: deposition of thin films on porous alumina, deposition of films on nanofibers made with a porous alumina template, deposition of thin films on nanofibers either on natural fibers like cellulose or electrospun polymer nanofibers. The oxide nanotubes are obtained by annealing in air the TiO2 coated nanofibers and thereby removing the carbohydrate kernel. Photocatalytic activity of the nanomaterials were studied by decomposing methylene blue. The photocatalytic activity could be enhanced by coating the material with noble metal nanoparticles. Reusable magnetic nanofibers were obtained by coating electrospun iron acetate composite fibers with ALD TiO2. INOR 29 Carbon dioxide as a carbon source for synthesis of carbon nanotubes by chemical vapor deposition Xiang-ju Xu, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China, daisyxxj2003@yahoo.com.cn Carbon dioxide was successfully used as carbon source in synthesis of carbon nanotubes(CNTs) by chemical vapour deposition(CVD) over Fe/CaO catalyst. The influence of some reaction parameters, including carbon source, furnace temperature, and types of support media is discussed in this paper. The product was evaluated using both Transmission electron microscopy(TEM) and Raman spectroscopy. Straight, crooked and branching structures of multi-walled carbon nanotubes(MCNTs) were discovered from the TEM micrographs of product. Their average diameters are about 50 nm. Raman spectrum results show that the nanotubes grew perfectly. The formation mechanism of MCNTs in this process was also studied. INOR 308 Thiol group sidewall functionalization of single walled carbon nanotubes Heather L. Rhoads1, Christopher N. Brammer2, Donna J. Nelson1, and Ruibo Li1. (1) Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, Fax: 405-325-6111, hrhoads@ou.edu, (2) Department of Chemical, Biological, and Materials Engineering, University of Oklahoma Since their discovery, there has been an intense effort to characterize single walled carbon nanotubes (SWNTs) and to understand their properties. This information will allow researchers to develop SWNTs for applications intended to improve all aspects of life from medical to electrical and mechanical technology. Several characterization techniques, such as Raman, near-IR, UV-Vis, and TGA have been employed for years to characterize SWNTs, but more recently, NMR was found to be useful for determining both type and degree of functionalization. Such information will enable more direct syntheses for precise control of nanomaterial applications. To our knowledge, we report the first NMR spectra demonstrating thiol group sidewall functionalization; NMR data are analyzed in conjunction with Raman, FTIR, UV-Vis, and TGA data. In addition, a brief discussion of planned applications for our product's photoelectric properties will be presented. INOR 339 Potassium intercalation of graphitic nanofibers Jason A. Michel and Charles M. Lukehart, Department of Chemistry, Vanderbilt University, 1822 VU Station B, Nashville, TN 37212, Fax: 615-343-1234, j.michel@vanderbilt.edu Graphitic nanofibers (GNFs), grown by catalytic decomposition of carbonaceous gases, were reacted with potassium metal to form intercalation compounds. Three types of graphitic nanofiber were employed, namely platelet, herringbone, and narrow tubular herringbone, each with unique morphology. The air-sensitive stage 1 and stage 2 intercalation compounds were characterized by powder XRD. Thermionic electron energy distributions (TEED) show that the stage 1 intercalation compound has a work function of φ=2.2 eV, as compared to φ=4.7 eV for pristine GNFs, a reduction of 2.5 eV. The intercalation compounds have also been shown to initiate the polymerization of olefins such as isoprene and styrene to form GNF-polymer composites. INOR 350 Palladium nanoclusters on carbon nanotubes for flexible hydrogen sensors Yugang Sun, Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, ygsun@anl.gov, H. Hau Wang, Materials Science Division, Argonne National Laboratory, Qing Cao, Department of Chemistry, University of Illinois at Urbana-Champaign, and John A. Rogers, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign Hydrogen sensing represents an important technique in a wide range of applications for ‘hydrogen economy' such as industrial processing, fuel cells, hydrogen storage and separation, etc. Conventional hydrogen sensors are fabricated, in general, on rigid substrates (e.g., glass, quartz, silicon wafers) by using continuous as well as discontinuous palladium films (or wires) with lateral dimensions on the nanometer scales. The rigidity (and/or fragility) of these devices somehow limits their application in systems with curvilinear surfaces that require conformal lamination and mechanical shock-resistance. In contrast, hydrogen sensing devices fabricated on flexible polymeric substrates can find applications complementary to that of the conventional sensors on rigid substrates. We have recently found that nanoclusters of palladium deposited on the support of networks of single-walled carbon nanotubes significantly change the transport property of carbon nanotubes when the composites are exposed to hydrogen. Printing thin films of the Pd/nanotube composites on poly(ethylene terephthalate) (PET) sheets generates light-weight, shock-resistive, flexible hydrogen sensors. The as-fabricated devices have excellent performance which is comparable (even higher) to the conventional sensors. For example, these sensors can detect hydrogen with concentration as low as 30 ppm in air. The response time is as short as 7.5 second when the devices are exposed to 0.1% hydrogen in air at room temperature. [ Last edited by lingyun79 on 2007-3-25 at 14:26 ] |
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INOR 368 Synthesis of colloidal II-VI and IV-VI metal sulfide semiconductor nanowires by the solution-liquid-solid growth mechanism Jianwei Sun and William E. Buhro, Department of Chemistry, Washington University, 1 Brookings Dr, Campus Box 1134, Saint Louis, MO 63130, jsuna@artsci.wustl.edu High-quality monodisperse crystalline semiconductor nanowires (NWs) are of both scientific and technological interest due to their wide range of optical and electrical properties. Here we demonstrate the synthesis of colloidal II-VI and IV-VI metal sulfide semiconductor NWs via the solution-liquid-solid (SLS) growth mechanism developed by our group. The NWs are grown by using single-source metal diethyldithiocarbamate precursors and Bi nanoparticles serving as the catalyst in trioctylphosphine oxide (TOPO) solvent. The structure of the NWs is determined by XRD and TEM studies. The absorption and the photoluminescence properties are also studied, which demonstrate quantum-confinement effects. INOR 369 Synthesis of silicon carbide nanotubes by chemical vapor deposition Nongyue He, State Key Laboratory of Bioelectronics, Southeast University, 210096 Nanjing, China, Fax: 86-25-83790885, nyhe1958@163.com, Deliang Tao, Hunan Key Laboratory of Green-Packaging and Application of Biological Nanotechnology, Hunan University of Technology, Zhengfang Xie, State Key Lab of Advanced Ceramic Fibers & Composites, National University of Defense Technology, and Song Li, Hunan Key Laboratory of Green Packaging and Application of Biological Nanotechnology, Zhuzhou Institute of Technology, Wenhua Lu, Zhuzhou 412008, China, Fax: 86-733-2182097, solisong@163.com Silicon carbide (SiC), a typical non-oxide ceramic compound with excellent oxidization resistance, outstanding corrosion resistance, high thermal conductivity with low thermal expansion coefficient, high hardness and abrasion resistance, has been paid great attention. Silicon carbide nanotubes (SiCNTs) were directly synthesized here by chemical vapor deposition (CVD). Methyltrichlorosilane was selected as SiC gaseous source, ferrocence and thiophene as the catalyst and the cocatalyst, respectively. The influences of reaction temperature, contents of catalyst and cocatalyst, and content of gaseous source on morphologies of the products were investigated, respectively. The products were identified by high-resolution transmission electron microscopy, scanning electron microscopy, x-ray diffraction and energy-dispersive x-ray, respectively. The synthesis of SiCNTs by CVD is a condition-dependent process. SiCNTs with 20~80 nm in outer diameter and 15~35 nm in inner diameter were observed. The wall structure similar to that of carbon nanotubes was not found for the SiCNTs. INOR 370 Nanoparticle size and self-assembly within nanoclay hybrid films Michael Nolan Jr. and Michael E. Hagerman, Department of Chemistry, Union College, Schenectady, NY 12308, nolanm2@union.edu Comparisons of the inclusion chemistry of Laponite and other synthetic hectorite films offer routes to examine the influence of nanoparticle size and interlamellar cations on organic guest entrapment and host-guest interactions that mediate self-assembly. We have used various cationic rhodamine dyes included within these nanoclay hybrid films as photoprobes of organic-inorganic interfaces and film nanoarchitectures. Detailed optical analyses including electronic absorption and fluorescence spectroscopy have afforded study of how the fluorescence properties of rhodamine changes with respect to concentration and nanoscaffold binding location. Spectral red shifts in both absorption and emission indicated that the chromophores formed J-aggregated dimers with maximum luminescence at very low guest concentrations. H-aggregation and higher order aggregates with reduced luminescence were observed at higher guest loadings. These studies offer synthetic routes for selective tuning of organic-silica interfaces with important implications for future work on optoelectronic devices and gas sensors. INOR 371 Naturally occurring fluorescent (NOF) mineral inspired luminescent colloidal nanocrystals Timothy N. Lambert1, Bernadette A. Hernandez-Sanchez1, Timothy J. Boyle1, Harry D. Pratt III1, Nicholas L. Andrews2, Diane S. Lidke2, Janet M. Oliver2, and Bridget S Wilson2. (1) Advanced Materials Laboratory, Sandia National Laboratories, 1001 University Blvd SE, Albuquerque, NM 87106, Fax: (505)-272-7304, tnlambe@sandia.gov, (2) Department of Pathology, The University of New Mexico Health Sciences Center In an effort to develop new non-cytotoxic luminescent colloidal nanocrystals (NCs) for live cell imaging, we have initiated a NIH-funded program to prepare and evaluate new nanoprobes based on naturally occurring fluorescent (NOF) minerals and lanthanide-doped ceramic oxides. The major goals are to develop new probes that are highly fluorescent, bio-compatible, non-toxic, and tunable. With this in mind we have prepared sphalerite [(Fe/Zn)S], scheelite [Ca(WO4)], manganoan [(Mn/Ca)CO3] and perovskite (CaTiO3) inspired nanomaterials and lanthanide (Dy, Nd, Eu, Tb, Er) doped ceramic oxides, utilizing solution precipitation and solvothermal methods. Surface capping with functionalized poly(ethyleneglycol) molecules/lipids has yielded water soluble NCs that are currently being evaluated for their luminescent properties, as well as their non-toxicity and ability to report on cell-signaling events with various cell lines. The synthesis, materials characterization, water-solubilization methods, biocompatibility and cell-signaling efforts to date will be presented. This work supported by the Department of Energy, Office of Basic Energy Sciences and the United States Department of Energy under contract number DE-AC04-94AL85000. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy. INOR 372 Synthesis and characterization of mono and multi-element (Nb,Ru)-MSU molecular sieves Izabela Nowak1, Agnieszka Feliczak1, and Mietek Jaroniec2. (1) Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland, Fax: +48-61-8658008, nowakiza@amu.edu.pl, (2) Department of Chemistry, Kent State University Mesoporous (Nb,Ru)MSU-X materials have been successfully prepared for the first time by using tetraethyl orthosilicate, ammonium trisoxalate complex of niobium(V), chloropentaamineruthenium(III) chloride and fatty alcohol polyoxyethylenepolyoxypropylene ether as the sources of silicone, niobium and mesostructure-directing agent, respectively, at different pH values of the synthesis gel. The use of p-octyl phenyl derivatives having different number of PO groups, i.e., 7 or 14, led to the formation of samples of different pore sizes. All the (Ru,Nb)-MSU samples showed diffraction patterns typical for mesostructured materials with a worm-like ordering. The resulting materials featured high surface area (500-1000 sq. m/g), large porosity (mesopore volume up to 0.8 cu. cm/g) and uniform pore size (pore width range: 2.5–6 nm). It appears that ruthenium and niobium were incorporated into the pore walls of these materials. INOR 373 Effect of synthesis method on the physical and catalytic property of nanosized NiO Feng Yang, Ying Wu, Tinghua Wu, and Huilin Wan, Institute of Physical Chemistry, Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Zhejiang Normal University, Jinhua 321004, China, ying-wu@zjnu.cn, ying-wu@zjnu.cn In recent years there has been an increasing interest in the synthesis of nanosized crystalline metal oxides. The physicochemical property of nanoparticles has intimate connection with the preparation technique. Nanosized NiO material was prepared by different methods. It's obvious that synthesis techniques influence the size, shapes and distribution of NiO nanoparticls. Therein NiO prepared by sol-gel and reverse micro-emulsion method has the larger special surface area and better particle distribution, compared with solid-state milling and precipitation method. The special surface area of NiO nanoparticles influences the adsorptive property, which has intimate connection with their catalytic behavior. The undecomposed surfactant covering the partial surface of NiO prepared by micro-emulsion method and calcinated at low temperature restrained its adsorption. Thus, NiO nanoparticles prepared by sol-gel method have good adsorptive property and best catalytic behavior for oxidation dehydrogenation of ethane reaction at lower reaction temperature. INOR 374 Effects of solvent on properties of TiO2 porous films prepared by a sol-gel method from the system containing PEG Jinfei Luo and Xiaoxin Liu, School of Chemical Engineering & Technology, Tianjin University, Weijin road 92, Tianjin 300072, China, Fax: 86-22-87401961, luojinfei@tju.edu.cn Four different solvents were used to prepare porous TiO2 films by the sol-gel method from the system containing tetrabutylorthotitanate as starting material and PEG as a template. The comparison of effects of the four solvents on the porous structure, film thickness, crystallization behavior from amorphous to anatase and optical properties of the resultant TiO2 porous films are discussed. The maximum thickness of the film prepared by one-run dip-coating reaches over 1.17 ìm when 1-decanol is used as the solvent. The mechanism for formation of the porous structure is interpreted based on the phase separation and self-assembly of PEG in the sol systems. |
12楼2007-03-25 14:19:37
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INOR 375 Gold nanoparticles coated with redox-active transition metals Abril A. Ramirez1, Itzia Cruz-Campa1, and Juan C. Noveron2. (1) Chemistry department, University of Texas at El Paso, 500 W. University, El Paso, TX 79968, Fax: 915-747-5748, (2) Department of Chemistry, University of Texas at El Paso The project consist of the synthesis and characterization of metal-binding ligands with a motif that allow them to bind to the surface of gold nanoparticles (5 nm). We have designed an eleven carbon chain ligand containing a thiol end that will react with the gold nanoparticle and a triacylciclononane moiety on the opposite end that will interact with metal ions. Upon introduction of transition metal salts, such as Zn(II) or Cu(II), the metal complexation will occur on the surface and generate a polycationic particle with a specific size and charge density. We will report data from atomic force microscopy (AFM), Extended X-ray Absorbance Fine Structure (EXAFS), and cyclic voltammetry. INOR 377 Sacrificial DNA templates for highly parallel nanolithography Hector A. Becerril and Adam T. Woolley, Department of Chemistry and Biochemistry, Brigham Young University, C-100 BNSN, Provo, UT 84602, hab@chem.byu.edu DNA is used extensively in nanofabrication to produce discrete and periodic nanostructures. These often serve as templates for selective deposition of metals, semiconductors, nanotubes, proteins, etc. The properties of DNA-templated nanostructures are directly and often adversely influenced by the nucleic acid within. To solve this problem, we report the use of DNA as a sacrificial template. We form DNA patterns on Si or SiO2 surfaces, and utilize thin-film deposition and anisotropic etching to transfer these features into the substrate with high fidelity. The patterns formed are DNA-free and can be processed using microfabrication techniques to form distinct nanostructures on surfaces in a highly parallel fashion. While the shape and dimensions of the final nanostructures resemble the DNA template, their mechanical and electrical properties are independent of the templating material. This new type of molecular lithography should be useful for the rapid and inexpensive patterning of nanostructures with <30 nm linewidths. INOR 378 Shaped core-shell nanostructures: Shaped synthesis of gold nanoshells with tunable optical properties on silica nanospheres Yan-Li Shi and Tewodros Asefa, Department of Chemistry, Syracuse University, Syracuse, NY 13244, yashi@syr.edu Metal nanoshells, which are composed a thin metal shell such as gold and silver on a dielectric silica core, are classes of nanomaterials with highly tunable optical properties. The plasmon resonance of these nanomaterials can be shifted throughout the visible and near infrared by varying the ratio of the core radius to the shell thickness. These nanoshell materials have recently been demonstrated to have great promising applications from treating cancer cells to bioimaging. These earlier synthetic methods were, however, mainly concentrated at producing size-controlled spherical particles having low polydispersity. The shaped control synthesis of many nanomaterials is now known to result in unique properties that their spherical counterparts do not offer. The recent work in our group involving shaped synthesis of nanomaterials using seeds, additives, and various types of reagent have demonstrated that the synthesis of shaped nanoshells with unique optical, tunable absorption in the near IR region is possible. These shaped nanoshells have triangle, pentagon, hexagon and urchin-like shapes. They also exhibit a red-shifted plasmon absorbance to NIR range depending on the thickness of their shaped nanoshells. These materials may have potentially wide ranges of applications for nanoelectronics, surface enhanced Raman scattering (SERS), chemical analysis and biological assays. INOR 447 High resolution core and valence band XPS of non-conductor silicates G. Michael Bancroft1, VPAlya Zakaznova-Herzog2, H. Wayne Nesbitt2, and John S Tse3. (1) Department of Chemistry, University of Western Ontario, London, ON N6A 5B7, Canada, Fax: 519-661-3022, gmbancro@uwo.ca, (2) Department of Earth Sciences, University of Western Ontario, (3) Physics and Engineering Physics, University of Saskatchewan Good XPS spectra of non-conductors have been difficult to obtain in the last 40 years, mainly due to charging and differential charging problems. A novel Kratos Axis Ultra magnetic confinement charge compensation system makes it possible to eliminate differential charging on non-conductors, and obtain as narrow linewidths as previously obtained on semi-conductors. High quality core level ( eg. Si 2p, O 1s, Ca 2p, Mg 2p) and valence band spectra of quartz, olivines, and pyroxenes have been obtained on fractured and hydrated surfaces. Total core level linewidths of ~1.2 eV (compared to close to 2 eV for previous spectra) are observed, and these linewidths arise from M-O (M=Si, Ca, Mg) vibrational structure in the ion state. Both O 1s and valence band spectra are very sensitive to the different silicate structures. The three peaks in the O 1s spectra of pyroxenes are assigned to the major three structural O in the Si2O6 unit. High quality calculations of the valence bands (including a hydrated olivine) yield theoretical XPS valence band spectra that are in excellent agreement with the experimental spectra. |
13楼2007-03-25 14:20:03