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  • 1
    Electronic Resource
    Electronic Resource
    Optical transitions in (ZnCo)Se and (ZnFe)Se: Role of an effective p–d exchange (invited) : 38th Annual Confrerence on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5719-5724 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we discuss photoluminescence (PL) and Raman excitations in the diluted magnetic semiconductors Zn1−xCoxSe and Zn1−xFexSe. The PL spectra associated with isolated crystal field d levels are found to rapidly weaken and/or broaden as the transition metal ion concentration approaches and increases beyond a critical value. In addition a Raman continuum, that overlaps with the optical phonon, is observed to develop when the PL features are modified. In the corresponding Zn1−xCoxSe samples the optical phonons acquire a characteristic Fano line shape suggestive of its coupling to the Raman continuum. It is proposed that these changes to the optical transitions arise from the enhancement of an effective p–d hybridization between low-lying d levels and band electrons with increasing x—an effect largely due to the proximity of the Co2+ and Fe2+ crystal field ground levels to the valence band maximum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355594
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  • 2
    Electronic Resource
    Electronic Resource
    Scaling behavior of dynamic correlation effects (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 147-157 
    Details
    ISSN: 0020-7608
    Keywords: dynamic correlation effects ; perturbation theory ; MBPT ; multireference perturbation theory ; scaling theory ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present an analytical estimate of the intrinsic errors of second-order perturbation theory in the complete basis set limit in the framework a scaling theory, which employs the maximal “sharpness” of the orbitals in a given basis set, quantified by the average momentum, as its fundamental variable. We find that the intrinsic errors of second-order perturbation theory fall with the third inverse power of the maximal momentum representable in the basis set, while the basis set truncation errors fall with the second inverse power of the momentum. These analytical arguments are verified in a numerical investigation employing distributed basis sets of up to 600 orbitals for the helium atom, water, and ethene. Extending our analysis to generic multireference perturbation theory (MRPT) we find that the leading contribution for the relaxation of the orthogonal complement of the zero-order wave function in the primary space scales with the same power as the leading overall perturbative correction, which yields an analytical argument for the perturbation inclusion of such feedback effects in the formulation of efficient versions of MRPT.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 147-157, 1998
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Phenol/cresol-formaldehyde resin characterization and contribution to product hardness (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 257-262 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Lot-to-lot variations in a phenol/cresol-formaldehyde resin were fully characterized. Resin property-product hardness relationships were examined to elucidate the cause of variable hardness in product insulators and to establish acceptance criteria for the resin. A high methylol content (φCH2OH), determined by quantitative carbon-13 nuclear magnetic resonance (13C-NMR), and a narrow molecular weight distribution (MWD), determined by size exclusion chromatography, were found necessary for resin to produce insulator meeting the minimum Shore D durometer specification of 40.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300502
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    Paper (German National Licenses)
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