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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of inclusive nucleon spectra fromp- andα-induced reactions in the frame of the INDEX model, and implications for stopped π−-induced reactions (1987)
    Springer
    The European physical journal 328 (1987), S. 445-453 
    Details
    ISSN: 1434-601X
    Keywords: 24.60.Dr ; 24.60.Gv ; 25.80.Ls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The previously published INDEX model is tested for nucleon spectra fromp- andα-induced reactions. The results of two alternative versions, the INCLUSIVE INDEX model and the EXCLUSIVE INDEX model, quite well agree with the data. It is found that in the INCLUSIVE INDEX model three preequilibrium stages are sufficient to describe single- and multi-nucleon emission. The model provides an useful first order estimate of the influence of the finite Fermi energy on particle spectra. This effect is very strong for nucleon induced reactions while forα-induced reactions it can be neglected. The deduced mean-free-path multiplier corroborates the long stated discrepancy between models in which excitons interact independently or not. Using preequilibrium parameters similar to those found for nucleon induced reactions the important branching ratio of contributingnp andpp pairs in stoppedπ −-absorption can be determined by INDEX model calculations. Deduced values from publishedn- andp-spectra agree reasonably well with those of other experimental analyses but deviate significantly from microscopic model predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289630
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  • 2
    Electronic Resource
    Electronic Resource
    Ion Pair Amphiphiles from Sodium Dodecyl Sulfate and Ammonium Amphiphiles Carrying Functionalized Azobenzene Units (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1719-1724 
    Details
    ISSN: 0947-3440
    Keywords: Thermotropic and lyotropic phase behavior ; Amphotropes ; Surfactants ; Liquid crystals ; Chromophores ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New ammonium amphiphiles having a N,N-dimethyl-N-hydroxyethylammonium headgroup and various azobenzene mesogenic units connected by a decyl or dodecyl spacer have been synthesized. The azobenzene unit is functionalized at the 4-position with a cyano, methoxy or fluoro substituent. For the cyano-substituted amphotropes and the fluoro compound with a dodecyl spacer a smectic phase is formed as was observed by differential scanning calorimetry and polarization microscopy. Complexation with sodium dodecyl sulfate, SDS, in a 1:1 molar ratio induces the formation of a smectic phase for the compounds with a decyl spacer. The compounds with a dodecyl spacer showed rather complex behavior attributed to different crystal morphologies. The ammonium amphotropes form aggregates in water when heated above their Krafft temperature. However, these aggregates are not stable and crystallize upon cooling. The ion pair amphiphiles with SDS as second component form vesicles in water as observed by optical and electron microscopy. The observed blue shift in the UV absorption maximum of the amphotropes upon addition of SDS indicates π-π stacking between mesogenic units resulting from aggregation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970813
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  • 3
    Electronic Resource
    Electronic Resource
    Monolayer and Bilayer Stability of Ammonium Amphiphiles Carrying an Azobenzene Unit - Effects of Substituents at the Azobenzene Unit (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 21-26 
    Details
    ISSN: 0947-3440
    Keywords: Mesogenic unit ; Monomer exchange ; “Gel-to-liquid crystalline” phase transition ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel double-chained ammonium amphiphiles carrying one azobenzene moiety (I) have been synthesized. The bilayer-stabilizing effect of different azobenzenes (ABs) has been investigated by measuring the “gel-to-liquid crystalline” phase transition temperatures of the formed bilayers in water using differential scanning calorimetry. It is found that the stabilizing effect of the azobenzenes strongly depends on the substituents at the aromatic ring. The stabilizing effect increases in the sequence F 〈 H 〈 NO2 〈 CN 〈 OCH3 〈 N=N-Ph, which cannot be correlated with the electron-withdrawing or -donating properties of the substituents. It is concluded that dipole-dipole interactions between the ABs are of minor importance for the overall stabilization of the bilayer. Instead, other factors determine the strength of the van der Waals interactions between the ABs. In the bilayers the ABs form H-aggregates as is observed by the blue shift of the UV absorption maximum. This blue shift is not affected by the “gel-to-liquid crystalline” phase transition. Bilayers of I-N=N-Ph do not exchange monomers with vesicles of didodecyldimethylammonium bromide, whereas all other investigated bilayers do. Compound I-N=N-Ph forms monolayers at the water-air interface, which are much more stable than the monolayers of the other investigated compounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970106
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