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  • American Institute of Physics (AIP)  (32)
  • American Chemical Society (ACS)  (8)
  • Periodicals Archive Online (PAO)  (5)
  • 1
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    Management Accounting in Australia (1960)
    Menasha, Wis. : Periodicals Archive Online (PAO)
    The Accounting Review. 35:3 (1960:July) 464 
    Details
    ISSN: 0001-4826
    Topics: Economics
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:5030-1960-035-03-000011
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  • 2
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    Water uptake profile in a model ion-exchange membrane: Conditions for water-rich channels (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-03-20
    Description: Ionic conductivity in a polymeric fuel cell requires water uptake. Previous theoretical studies of water uptake used idealized parameters. We report a parameter-free prediction of the water-swelling behavior of a model fuel cell membrane. The model polymers, poly(methyl-butylene)-block-poly(vinylbenzyl-trimethylamine), form lamellar domains that absorb water in humid air. We use the Scheutjens-Fleer methodology to predict the resulting change in lamellar structure and compare with x-ray scattering. The results suggest locally uniform water distributions. However, under conditions where a PVBTMA and water mixture phase-separate, the two phases arrange into stripes with a dilute stripe sandwiched between two concentrated stripes. A small amount of water enhances conductivity most when it is partitioned into such channels, improving fuel-cell performance.
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics (AIP)
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  • 3
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    Interplay Between Hydroxyl Density and Relaxations in Poly(vinylbenzyltrimethylammonium)-b-poly(methylbutylene) Membranes for Electrochemical Applications (2018)
    American Chemical Society (ACS)
    Details
    Publication Date: 2018-01-24
    Description: Journal of the American Chemical Society DOI: 10.1021/jacs.7b10524
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society (ACS)
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  • 4
    Electronic Resource
    Electronic Resource
    Lowest energy excited singlet states of isomers of alkyl substituted hexatrienes (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 4691-4698 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibrationally resolved S0→S1 excitation spectra for the alkyl substituted linear polyenes heptatriene, octatriene, and decatriene seeded into a supersonic He expansion have been measured by resonance enhanced multiphoton ionization spectroscopy. As is the case for the parent compound hexatriene, the lowest energy excited singlet state in all of these molecules is the 2 1Ag state. The measurement of S0→S1 excitation spectra of three of the four double bond isomers of heptatriene gives a detailed picture of the dependence of the electronic structure of the 2 1Ag state on molecular conformation. The three isomers for which spectra are presented have the cis configuration at either the central or the alkyl substituted double bond, or both. For the case of the mono cis species with the cis configuration at the alkyl substituted double bond the spectra show the presence of two single bond conformers. Because of the increased number of distinguishable isomers and conformers for octatriene and decatriene we were unable to unambiguously separate the observed spectra of these molecules into contributions from single specific molecular conformations. However, the increased excitation intensity in the low frequency region relative to that in the C–C and C=C stretching region for octatriene and decatriene as compared to heptatriene suggests that vibrational relaxation is enhanced in the more complex molecules. In the case of unsubstituted hexatriene, previously reported spectra show that the 2 1Ag state has lower symmetry than does the ground state (most likely due to nonplanarity at the terminal carbon atoms). There is no evidence for an analogous distortion in the excitation spectra measured for the alkyl substituted hexatrienes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460581
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  • 5
    Electronic Resource
    Electronic Resource
    Lowest energy excited singlet state of 2,2':5',2''-terthiophene, an oligomer of polythiophene (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 3506-3510 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Fluorescence excitation and emission spectra have been measured for solid solutions of 2,2':5',2‘-terthiophene in n-decane at 77, 10, and 4.2 K. At 4.2 K the spectra exhibit full vibrational resolution (origin inhomogeneous FWHM approximately 5 cm−1). At 4.2 K narrow band excitation and detection establish that there are four independent but nearly identical excitation/emission pairs with origins at 24 806, 24 827, 24 835, and 24 879 cm−1. Whether this multiplicity is caused by the presence of different isomers or comes from a single isomer that can occupy in the n-decane lattice in four different ways is not known with certainty. However, the similarity of the vibronic development and energetic considerations suggest that the spectra arise from a single isomer present in four rather similar n-decane sites or from four slightly different conformations of a single isomer. The overlap of excitation and emission origins and the vibrational development of the spectra establish that the S0 to S1 transition is symmetry allowed (probably reasonably described as the 1 1A1 to 1 1B2 transition where the excited state is derived from the ground state by the promotion of one electron from the HOMO to LUMO).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455861
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  • 6
    Electronic Resource
    Electronic Resource
    Photochemical hole burning for 1,3,5,7-octatetraene in n-hexane (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 3038-3042 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is now well established that the unsubstituted linear polyene 1,3,5,7-octatetraene efficiently undergoes cis–trans photoisomerization even when substituted in an n-alkane matrix cooled to liquid-helium temperatures. The fact that this photochemical reaction takes place under these conditions opens the possibility of using the techniques of photochemical hole burning to uncover details of the microscopic mechanism of this isomerization. In this paper we report the demonstration of photochemical hole burning for all-trans-octatetraene in n-hexane, show that the hole width for the zero-phonon component of the 0–0 band in the limit of zero temperature and zero hole depth is within experimental error equal to the value predicted from the measured fluorescence lifetime, analyze the dependence of hole width on temperature, and show that the relative quantum yield for hole burning increases by approximately a factor of 35 as vibrational energy in the excited state is increased beyond a threshold of approximately 950 cm−1. This threshold agrees well with the previously determined barrier to trans, cis isomerization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455906
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  • 7
    Electronic Resource
    Electronic Resource
    Location of the 2 1Ag state in hexatriene (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 4622-4623 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458574
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  • 8
    Electronic Resource
    Electronic Resource
    The lowest excited singlet state of isolated 1-phenyl-1,3-butadiene and 1-phenyl-1,3,5-hexatriene (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 4860-4868 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report vibrationally resolved S0→S1 excitation spectra and vibronic level decay times for the phenyl-substituted polyenes 1-phenylbutadiene and 1-phenylhexatriene seeded in supersonic He expansions. This information was obtained using one- and two-color resonance-enhanced multiphoton ionization techniques. The shift in the excitation energy of the lowest excited singlet state upon deuteration of the phenyl ring demonstrates that in 1-phenylbutadiene S1 is mainly an excitation of the benzene ring while in 1-phenylhexatriene S1 is mainly the 2 1Ag state of hexatriene. Analysis of the excitation spectrum of 1-phenylhexatriene shows that the spectrum contains contributions from two species, the trans,trans and the trans,cis isomers, whose 2 1Ag state excitation energies differ by about 155 cm−1. The lifetimes of 2 1Ag zero-point levels and, in particular, the activity of the C–C and C=C stretch vibrations are markedly different for the two isomers. From these results we obtain a picture of the influence that the phenyl group has on such aspects of the electronic structure of the 2 1Ag state of hexatriene as the effective conjugation length, the symmetry properties, and the fluorescence quantum yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462776
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  • 9
    Electronic Resource
    Electronic Resource
    Electronic structure of thiophene and pyrrole dimers: 2,2'-bithiophene, 2,2'-thienylpyrrole, and 2,2'-bipyrrole (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 4783-4789 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibrationally resolved fluorescence and fluorescence excitation spectra have been measured for solid solutions of 2,2'-bithiophene, 2,2'-thienylpyrrole, and 2,2'-bipyrrole in n-hexane at 4.2 K. The vibronic development of the spectra of all three molecules is very similar to what has been reported previously for longer polythiophene oligomers. Bithiophene and thienylpyrrole have similar S0 to S1 excitation energies: 29 603 and 30 006 cm−1, respectively. The S0 to S1 excitation energy of bipyrrole is significantly higher, 32 720 cm−1, indicating nonplanarity of the pyrrole rings. The vibrational development of the spectra and coincident origin energies in excitation and emission establish that the S0 to S1 transition is symmetry allowed for all three molecules, reasonably described in simple molecular orbital theory as the promotion of one electron from the highest energy occupied molecular orbital (HOMO) to the lowest energy unoccupied molecular orbital (LUMO).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461721
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  • 10
    Electronic Resource
    Electronic Resource
    Lowest energy excited singlet state of isolated cis-hexatriene (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 6367-6376 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In a previous letter [J. Chem. Phys. 92, 4622 (1990)] we reported the first observation of the 2 1Ag state of cis-hexatriene in a supersonic jet expansion by using resonance enhanced multiphoton ionization spectroscopy. Here, the vibrational analysis of the 1 1Ag→2 1Ag excitation spectrum of cis-hexatriene is presented. The excitation spectrum shows that cis-hexatriene in the 2 1Ag state deviates slightly from planarity; a conclusion which is corroborated by ab initio calculations indicating that the nonplanarity primarily involves the terminal hydrogen atoms. Except for observable intensity in the low frequency modes associated with the small out of plane distortion, the vibronic development of the 1 1Ag→2 1Ag transition in cis-hexatriene is similar to that observed for other polyenes: the 0–0 transition is the most intense feature and the next most intense band is the C(large-closed-square)C stretching fundamental. Thus the general features of the electronic structure of the cis-hexatriene 2 1Ag state are analogous to those of other polyenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460315
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