Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (3)
  • 1
    Electronic Resource
    Electronic Resource
    The geometric and electronic structure of small copper clusters Cun and Cu+n (n=1–3) by an effective core potential method (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 4633-4640 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electronic structure calculations have been carried out for the total energy of the ground state of Cun and Cu+n (n=1–3) clusters. The Cu atom is treated as a one-electron system and the effect of the core is approximated by a shape consistent pseudopotential and a semiempirical core-valence, core–core polarization potential. The exchange and correlation energies among the valence electrons are treated by the local-spin-density-functional approximation with and without the self-interaction corrections (SIC). The binding energy and bond distance of Cu2 calculated with SIC are in almost exact agreement with experimental data. The calculated ionization potentials exhibit even–odd oscillations as a function of n. The potential energy surfaces of Cu3 show substantial differences when obtained with and without SIC. The most stable geometry predicted by the latter is an acute triangle with an apex angle of 47° and a long bond length of 5.41 a.u. In terms of a distortion parameter ρ with respect to an equilateral triangle with an equilibrium bond length of 4.78 a.u. we have ρ=0.435 a.u. This is in excellent agreement with the experimental value of ρ=0.472 a.u. The calculated binding energy of Cu3 with respect to fragmentation into Cu atoms is 2.259 eV in comparison with the experimental value of 3.108±0.135 or 3.058±0.151 eV. The 27% error is probably due to the use of local exchange-correlation energies and the somewhat small basis set.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448720
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Studies on the imidization of N-substituted polymaleamic acids (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 15-29 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A spectral method for determining the imidization from maleamic acid to maleimide was described. The formation condition and mechanism of polymaleimide compared with N-phenyl-maleimide (I) and 4,4′-bis(N-maleimido)-diphenylmethane (II) were investigated. A series of N-substituted maleimides were synthesized by the reaction of their corresponding maleamic acids with acetic anhydride and sodium acetate as a catalyst. The rate of dehydration reaction of N-phenylmaleamic acid with Ac2O was determined at a mole ratio 0.1:1 of NaOAc to N-phenyl-maleamic acid and a second-order constant K of 1.38 × 10-2 (mL/mol s) was obtained. The activation energies for the ring-closure reaction of N-phenylmaleamic acid and polyphenylene-methylenemaleamic acid were 1.26 × 104 (cal/g mol) and 1.32 × 104 (cal/g mol), respectively. The decreasing order for the rate of N-substituted maleimide formation was N-(p-methylphenyl)maleimide 〉 I ≒ II 〉 N-(p-chlorophenyl)maleimide. The result was attributed to the para-substituent effect. These imidization reaction were observed qualitatively by IR spectra and analyzed quantitatively by 1H-NMR spectra.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Syntheses of 4-methacryloxy-2,3,5,6-tetrabromobenzyl phosphonates and effects of flame retardancy on their Co-PMMA (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 3551-3567 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Methacryloxy-2,3,5,6-tetrabromobenzyl phosphonates (MTBBP) are prepared by the reaction of corresponding 4-hydroxy-2,3,5,6-tetrabromobenzyl phosphonates (HTBBP) with methacryloyl chloride. Comparisons of flame retardancy among the copolymers of methylmethacrylate (MMA) with MTBBP or with 4-methacryloxy-2,3,5,6-tetrabromotoluene(MTBT) and the mixture of poly(methyl methacrylate) (PMMA) with triphenyl phosphite reveal that the combination of phosphorus and bromine elements produces a synergistic effect on flame retardancy, and the chemical grafting of the fire-resistant elements into the polymer backbone gives a better effect than the physical mixing of their compounds with polymer. The unsatisfactory results of homopolymers of the synthesized methacrylate monomers prepared by free radical polymerization in solution may be due to their less reactivities; however, they can readily copolymerize with a liquid vinyl monomer such as MMA by means of bulk polymerization.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080271102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...