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
    Charge carrier statistics of semiconductors containing defects with negative electronic correlation energy (1982)
    Springer
    Applied physics 27 (1982), S. 39-47 
    Details
    ISSN: 1432-0630
    Keywords: 71.55.Fr ; 72.80.Cw ; 71.45.Gm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The free charge carrier concentration as a function of the reciprocal temperature and the doping level [p(1/T)- andp(C)-characteristics] is calculated from the neutrality equation of a semiconductor containing positive or negativeU centers. The typical exponential laws and power laws of thep(1/T)- andp(C)-characteristics are given both for positive and negative correlation energy of the bound charge carrier pairs. Furthermore, the characteristics are evaluated differentially, in order to obtain criteria for the presence of negativeU centers in semiconductors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197545
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Differential evaluation of the Hall effect in silicon with oxygen-related donors (1984)
    Springer
    Applied physics 33 (1984), S. 47-50 
    Details
    ISSN: 1432-0630
    Keywords: 71.55.Fr ; 72.80.Cw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The free-electron concentration as a function of the temperature is analyzed differentially for silicon with oxygen-related donors formed by annealing at 430 °C. The analysis yields defect levels atE c−0.25 eV,E c−0.14eV, andE c−0.055 eV assuming the degeneracy factors to be unity. The corresponding defect level concentrations are approximately proportional to the annealing time. Their formation rates are between 1 and 3×1010cm−3s−1 at 430 °C annealing temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197085
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The Cycloaddition of Allyl Cations to 1,3-Dienes: General Method for the Synthesis of Seven-Membered Carbocycles. New Synthetic Methods (40) (1984)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 23 (1984), S. 1-19 
    Details
    ISSN: 0570-0833
    Keywords: Cycloaddition ; Allyl cations ; Cations ; Synthetic methods ; Cycloheptanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of allyl cations and 1,3-dienes affords seven-, five-, and six -membered rings as well as products of electrophilic substitution and linear 1:1-adducts. In this review article, preparative and mechanistic advances are summarized with special emphasis on the synthesis of seven-membered carbocycles. For the first time, a comprehensive mechanistic description is presented: Three classes A, B, and C correlate product type and stereochemistry with the nucleophilicity of the diene, the electrophilicity of the allyl cation intermediate, and the donor capacity of the group Y attached to the central carbon of the allylic moiety. The problem “allylic resonance versus nucleophilic participation of Y” is discussed and experimental evidence is adduced for some participation of Y as a function of its nucleophilicity. For cyclopentenyl cations, enhanced charge separation and electrophilicity are postulated, even when Y is a good donor, due to the structurally enforced polarity of the π-allyl system.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198400013
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Syntheses of Seven- and Five-Membered Rings from Allyl Cations (1973)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 12 (1973), S. 819-835 
    Details
    ISSN: 0570-0833
    Keywords: Allyl cations ; Cyclization ; Cyclopentanes ; Cycloaddition ; Cycloheptanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cycloaddition of allyl cations to conjugated dienes offers an efficient and general tool for the construction of seven-membered carbocycles. The silver salt route is highly suitable for generating allyl cations and can be used even in most difficult cases, i. e. for elusive and intractable allyl cations such as 2-methylallyl, 2-methoxyallyl, and the parent allyl cation. Cycloadditions to the 2-methoxyallyl cation come very close to the prototype of a 6π, 7C reaction, since the carbonyl group introduced into the new ring can either be used for further transformations or be removed altogether. The combination of an allyl cation with π reactants, especially conjugated dienes, is a powerful and strongly convergent synthetic method since it permits one-step assembly, from a C3 and a C4 unit, of a cluster of up to four chiral centers in a ring which is larger than six-membered. Allyl cations combine with electron-rich 2π systems to form novel five-membered rings. The nature of the organometallic intermediates has been elucidated in many cases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197308191
    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...