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
  • 1
    Electronic Resource
    Electronic Resource
    Theoretical investigation of model polymers for eumelanins. I. Finite and infinite polymers (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2630-2636 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the electronic structure of ideal ordered polymers of 5,6-indolequinone, in one or other redox form. These molecules are the most abundant constituents of eumelanin, the pigment appearing in human skin. Our study is carried out through Hückel π-electron theory, which allows us to follow the trends in electronic structure from a single monomer—the isolated molecules—to finite polymers of up to 10 units, and to infinite polymers. We have chosen different polymerization directions which produce semiconducting chains. The comparison between finite and infinite polymers is very useful and leads us to propose a model that accounts for some of the known properties of eumelanins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457957
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Theoretical investigation of model polymers for eumelanins. II. Isolated defects (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 2848-2853 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate here defects in initially ordered polymers of 5,6-indolequinone, in one or other redox form. The defects studied include aggregation of the carboxyl radical into one skeleton monomer, the aggregation of a host monomer in a lateral misplaced position, and faults in the polymerization sequencing. Our study is carried out, as in the first paper I, through Hückel π-electron theory, and results are compared to the perfect structures in I. Our results indicate that the end-type defect suggested as an electron capture center in I is not deactivated by these other structural defects, and that new capture centers might be introduced that could also be responsible for the acceptor behavior of melanins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459676
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A parametric method 3 (PM3) study of trans-stilbene (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 3016-3021 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report a comparative modified neglect of diatomic overlap (MNDO), Austin method one (AM1), and parametric method 3 (PM3) study of trans-stilbene (tS) in its ground, excited (singlet and triplet), and ionic (positive and negative polarons and bipolarons) states. We have also calculated the barrier for ring rotation about the backbone single bond. Our results show that PM3 geometries are superior to MNDO and AM1, at least for tS. PM3 predicts, in contrast with MNDO, AM1 and even ab initio 3-21G, a coplanar structure for tS, in accordance with recent experimental data. Singlet and triplet energies obtained from heats of formation are in surprisingly good agreement with experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464128
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Spatially variable reaction in the formation of anodically grown porous silicon structures (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 590-592 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In porous silicon formations there is an increase of dissolution rate at the fluorine-covered sites of the silicon surface due to the presence of excess electrons coming from oxidation of molecular hydrogen at the passivated (hydrogen-covered) sites. The dissolution rate increase in the presence of excess charge at the fluorine-covered sites is experimentally measured and a theoretical investigation is carried out by a semiempirical Hartree–Fock calculation. This spatially variable dissolution generates the porous silicon surface. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360577
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Polymerization of 5,6-indolequinone: A view into the band structure of melanins (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 4088-4091 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present for the first time a study of finite and infinite polymers of 5,6-indolequinone. We show that the band structure of the infinite polymer presents semiconductor characteristics, and that the intrinsic paramagnetism of eumelanin can be modeled through electron trapping at deep "end-effect'' defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453810
    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...