摘要:

AbstractShortly after its discovery the electron was recognized as the carrier of electricity in metals. The difficulties encountered in treating the conduction electrons as a classical ideal gas was removed upon the advent of quantum mechanics and led to a satisfactory explanation of normal metallic conductivity. Although superconductivity was discovered more than fifty years ago, however, the first phenomenological theory did not come until the middle thirties and it took another twenty years before the first microscopic theory was presented. It was based upon the assumption that the conduction electrons formed a degenerate Bose gas but was soon replaced through the recognition that the pairing of electrons in a Fermi gas furnished a more realistic and quantitative explanation of superconductivity. The striking manifestation of superconductivity as a quantum phenomenon on macroscopic scale was demonstrated in the early sixties through the discovery of flux‐quantization in a closed superconductive ring and led shortly afterwards to the interesting related effects which arise from the introduction of a dividing barrie

ISSN:0449-2994    

DOI:10.1002/polc.5070290103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

摘要:

AbstractThe critical temperature, Tc, for all presently known superconductors does not exceed 21'K. This fact obviously limits the range of applications of superconductivity in technology in a very fundamental way. On the whole, the reason why the value of Tc for “ordinary” superconductors would not exceed 20‐40oK is fairly well understood. At the same time, there apparently could exist high temperature superconductors for which Tc would reach liquid air temperature or even room temperatures. Possible means of producing high temperature superconductors are considered in this article which is based on the review published inContemporary Physics, 9, 355 (1968), but includes also some new material. Special attention is paid to what can be called the exciton mechanism of superconductivity and its application to systems of the “sandwich” type and metallic conductors with layer s

ISSN:0449-2994    

DOI:10.1002/polc.5070290104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

ISSN:0449-2994    

DOI:10.1002/polc.5070290105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

摘要:

AbstractThe “Little” model for a macromolecular high temperature superconductor can be discussed in terms of its component parts. Studies on molecules designed to serve as the polyene and the polyene spine indicate that polymeric metallocenes, in which planar aromatic hydrocarbon rings and meatal atmos alternate, may be suitable. Toward this end the hydrocarbon dicyclopentanaphthalene, and various substituted derivatives were synthesized, and the polymerization of the corresponding dianions with ferrous chloride were investiga

ISSN:0449-2994    

DOI:10.1002/polc.5070290106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

摘要:

AbstractAttempts to synthesize conjugated polymers with cyanine dyes attached to the conjugated backbone are described. The experimental approach is to prepare and characterize conjugated polymers with attached quinolinium ions and then to convert these to dyes by reaction with lepidinium methiodide. Aromatic Schiff‐base polymers were chosen as the conjugated backbone. Since unsubstituted Schiff bases show very little conjugation, a series of model compounds and model polymers were prepared and their electronic spectra were determined in order to correlate the effect of substituents on electron delocalization. Efforts are being made to prepare high molecular weight polymers by a Schiff‐base exchange reaction. The syntheses of various monomers for the Schiff‐base exchange reaction are desc

ISSN:0449-2994    

DOI:10.1002/polc.5070290107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

ISSN:0449-2994    

DOI:10.1002/polc.5070290108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

摘要:

AbstractThe family of cyclic permethylpolysilanes, [(CH3)2Si]n, has been synthesized. Compounds in whichn= 5, 6 and 7 undergo reduction at low temperatures to form anion‐radicals. The five‐ and six‐membered rings give the parent anion‐radicals [(CH3)2Si]5− and [(CH3)2Si]6− when reduced electrolytically, but all three compounds give [(CH3)2Si]5− when reduced with alkali metals. The ESR spectra of the anion‐radicals show that the unpaired electron contacts all of the methyl protons equally, and so is fully delocalized over all the silicon atoms in the ring. The permethylpolysilanes have electron affinities similar to that of benzene; the ease of reduction is in the order [(CH3)2Si]5>benzene>[(CH3)2Si]6. These findings suggest that electron mobility and delocalization is not limited to “conjugated” molecules but can also be observed in systems not normally considered as “unsaturated.” Implications for the design of organic conducting ele

ISSN:0449-2994    

DOI:10.1002/polc.5070290109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

摘要:

AbstractThe structures and chemical, physical, and biological properties of porphyrins are generally described. The problems inherent in their employment in physical studies are summarized. A semiconduction study of Langmuir films of ms‐tetraphenylporphin showing a cubic thickness dependence in resistance is detailed. Possibilities for employing these materials in organic superconduction research are presente

ISSN:0449-2994    

DOI:10.1002/polc.5070290110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

摘要:

AbstractCopper porphins with cyanine dyes on the methine bridges show shifts compared to unsubstituted copper porphin of up to 0.5 electron volts of the near ultraviolet “Soret” absorption band. They show smaller shifts of the weaker visible band. This effect is explained as being due to an excitonic interaction with the cyanine dyes rather than the electron attracting or withdrawing effect of the d

ISSN:0449-2994    

DOI:10.1002/polc.5070290111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY

ISSN:0449-2994    

DOI:10.1002/polc.5070290112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1970

数据来源: WILEY