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  • 1
    Electronic Resource
    Electronic Resource
    Ultrafast relaxation processes of excitons to the relaxed excited state in one-dimensional dimethylglyoxime platinum complexes driven by intramolecular vibration (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 8687-8695 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Optical response due to the photo excited carrier or exciton dynamics in a one-dimensional (1D) dimethylglyoxime Pt complex [Pt(dmg)2] has been investigated by femtosecond pump–probe spectroscopy. Measurements were made at several excitation energies between the exciton state and the free electron hole pair state. Induced absorption was observed in the low-energy side of the exciton band at any excitation energy. The spectral shape of the induced absorption changed with time between 0.1 and 0.3 ps after instantaneous rise up. These results can be explained by the formation and thermalization processes of the relaxed excited state on the adiabatic potential surface. The unthermalized relaxed excited state is formed in a very short time (〈50 fs). From the Raman spectrum, the frequency of the intermolecular stretching mode along the chain was estimated to be 80 cm−1 (T∼400 fs). These facts suggest that, in contrast to other 1D systems such as polydiacetylenes (PDA) and halogen bridged mixed valence metal complexes (MX), the formation of the relaxed excited state is caused not by the stretching vibration along the 1D chain. We propose the possibility that the triggering of the primary relaxation is caused by a high frequency (〉600 cm−1) intramolecular mode which is not in the direction of the 1D chain. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478776
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  • 2
    Electronic Resource
    Electronic Resource
    Enhancement of the third-order nonlinear optical property of a one-dimensional platinum complex by fabricating its metastable form (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 13239-13246 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100035a031
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  • 3
    Electronic Resource
    Electronic Resource
    Sintering of Lanthanum Zirconate (1999)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Lanthanum zirconate (La2Zr2O7) was prepared by coprecipitating lanthanum nitrate and zirconyl oxychloride at pH 10, followed by ethanol washing. The initial high surface area of ∼304 m2·g−1 decreased very rapidly with increased sintering temperature and decreased to an immeasurably small value after heating at 1200°C for 15 h. The major parameters studied were phase evolution, crystallite size, porosity, surface area reduction, and shrinkage during sintering. Three temperature regions were identified based on these studies: below the crystallization temperature, between the crystallization temperature and ∼1100°C, and above 1100°C. The main contribution of surface area reduction in the region 800°–1100°C was due to surface diffusion; the main contribution above 1100°C was due to grain-boundary diffusion coupled with surface diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb02042.x
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of Peptization and Ethanol Washing on the Pore-Structure Evolution of Sol-Gel-Derived Alumina Catalyst Supports (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Alkoxide-derived boehmite precipitates were subjected to different post-precipitation treatments to obtain a peptized sol, an unpeptized slurry, and an ethanol-washed gel precipitate. These materials were dried further to obtain the corresponding gels. Changes in the surface area, porosity, and pore size with temperature and the phase-transformation behavior from gamma-alumina to alpha-alumina were studied using X-ray diffractometry, differential scanning calorimetry, and physical adsorption/desorption measurements. Gels that were obtained from the peptized sol retained the lowest porosity, in comparison to the ethanol-washed gel and the gel that was prepared from the aqueous slurry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02681.x
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  • 5
    Electronic Resource
    Electronic Resource
    Structure and Properties of Silica Derived from Silicon Alkoxide Reacted with Tartaric Acid (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of tartaric acid that was used in sol–gel processing on specific surface area, pore-size distribution, and gel structure of sol–gel-derived silica gels were investigated. The specific surface area of silicas that were calcined at 450°C increased from ∼600 m2/g to ∼1200 m2/g as the amount of tartaric acid that was used increased. The pore-size distribution changed as the surface area increased, and only the gels that had a surface area of 930-990 m2/g showed a very sharp pore-size distribution in the mesopore range. The difference in gel structure and properties was explained in terms of the acidity of tartaric acid and the inhibition of condensation among primary particles through the coordination or adsorption of tartaric acid on the particle surface. From the thermal behavior of the gels with different features, it was concluded that gel properties are determined not only by the structure of the precursor gel but also by the surface activity. The gel with uniform mesopores gave a high surface area over a wide range of calcination temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb03160.x
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  • 6
    Electronic Resource
    Electronic Resource
    Organozeolite materials and their properties (1999)
    Springer
    Catalysis surveys from Japan 3 (1999), S. 119-126 
    Details
    ISSN: 1572-8803
    Keywords: organozeolite ; microporous and mesoporous material ; inorganic-organic composite ; synthesis ; phosphonate ; aluminomethylphosphonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Attempts in developing organozeolites, namely microporous and mesoporous crystalline inorganic-organic composites with a zeolite-like three-dimensional framework and organic moieties covalently connected to the framework, are briefly reviewed. MCM-41 type mesoporous materials modified by organic functional groups have been prepared by use of organosiloxane as a part of Si sources and by post-modification of the purely inorganic materials using organosiloxane. Also, the incorporation of organic moieties into the zeolite frameworks has been tried. Recently, several novel metal organophosphonates with a three-dimensional framework, which can be regarded as organozeolites, have been prepared. Along with these new attempts, the authors' studies in preparation, structural analysis and gas adsorption properties of microporous aluminomethylphosphonates are introduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019023702312
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  • 7
    Electronic Resource
    Electronic Resource
    A new catalyst preparation by a combination of complexing agent-assisted sol–gel and impregnation methods (1998)
    Springer
    Catalysis letters 52 (1998), S. 49-53 
    Details
    ISSN: 1572-879X
    Keywords: catalyst preparation method ; ruthenium–tin–alumina ; combination ; sol–gel ; impregnation ; selective hydrogenation ; benzoic acid ; benzyl alcohol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The properties and preparation of a ruthenium–tin–alumina catalyst and its control by a combination of a complexing agent-assisted sol–gel method and an impregnation method have been investigated. It was found that the metal composition of the catalyst surface could be altered by use of the combination of the two preparation methods. Depending on the surface metal composition, the H2-adsorption ability and the hydrogenation activity of the catalysts could also be changed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019055016579
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  • 8
    Electronic Resource
    Electronic Resource
    Selective Formation of Spinel Iron Oxide in Thin Films by Complexing Agent-Assisted Sol-Gel Processing (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 77-81 
    Details
    ISSN: 1573-4846
    Keywords: iron oxide ; structural control ; complexing agent ; thin film ; sol-gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of iron oxide was controlled by regulating the hydrolytic polymerization of aquo iron complexes with organic polydentate ligands such as diols. Iron oxides were prepared by calcining the precursor polymers obtained from iron nitrate nonahydrate and diols. When the diols were 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol, α -Fe2O3 with corundum structure appeared exclusively or as the main crystalline phase, in spite of the amount of diol used and the calcination temperature. In the case of 1,2-decanediol and 1,2-dodecanediol, when five moles of the diols were used to one mole of iron nitrate and the calcination temperatures were below 400° C, γ -Fe2O3 with spinel structure appeared as the main phase and, when less than five moles of the diols were used, α -Fe2O3 appeared exclusively or as the main phase, irrespective of the calcination temperature. This tendency was also observed in thin films. Thus, a transparent magnetic film composed of γ -Fe2O3 could be prepared by applying a benzene solution of the iron polymer, obtained with 5 equivalents of 1,2-decanediol, on quartz and calcining the gel film at 350° C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026407306265
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of Organic Ligands Used in Sol-Gel Process on the Formation of Mullite (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 101-106 
    Details
    ISSN: 1573-4846
    Keywords: mullite ; organic ligand ; hydrolytic polymerization ; sol-gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The preparation of mullite by the sol-gel method using organic polydentate ligands and the effect of the raw materials and organic polydentate ligands on the formation of mullite were investigated. Two series of samples were prepared using tetraethoxyorthosilicate (TEOS) and aluminum nitrate nonahydrate, or dibutoxyethylacetoacetatoaluminum (Al(OBu)2(AcAcEt)) as the silica and alumina sources, respectively, and using ethylene glycol (EG), 1,3-propanediol (PD), 1,3-butanediol (BD), 2-methyl-2, 4-pentanediol (MPD), diethlene glycol monoethyl ether (DEME) and ethoxyethanol as the ligands. When the alumina source was aluminum nitrate nonahydrate, mullite was apt to appear in the order of EG 〉 PD 〉 MPD. When Al(OBu)2(AcAcEt) was the alumina source, the tendency toward the appearance of mullite crystalline phase was EG 〉 BD 〉 DEME 〉 MPD. Between the two alumina sources, aluminum nitrate nonahydrate gave mullite much easier than Al(OBu)2(AcAcEt). These relationships were discussed from the viewpoints of the coordination ability of the ligands and the miscibility between the silica and alumina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026467608991
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  • 10
    Electronic Resource
    Electronic Resource
    Control of refractive index of sol-gel tungsten oxide films (1996)
    Springer
    Journal of sol gel science and technology 6 (1996), S. 263-267 
    Details
    ISSN: 1573-4846
    Keywords: tungsten oxide ; sol-gel ; refractive index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Tungsten oxide films were prepared by a complexing agent-assisted sol-gel process. All the films were at 500°C were crystalline and transparent. The refractive index n and extinction coefficient k of the films were calculated from the transmittance and reflectance spectra in the visible and infrared regions. The values of n were lowered to depend on the organic ligands used in the preparation of the sols. The use of such ligands may be a mean to control the refractive index of coatings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402697
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