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  • 1
    Electronic Resource
    Electronic Resource
    Applications of holography in the investigation of photochemical reactions (1983)
    s.l. : American Chemical Society
    Accounts of chemical research 16 (1983), S. 218-224 
    Details
    ISSN: 1520-4898
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ar00090a006
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Second-order nonlinearity in poled-polymer systems (1994)
    s.l. : American Chemical Society
    Chemical reviews 94 (1994), S. 31-75 
    Details
    ISSN: 1520-6890
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cr00025a002
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Design of optimized photorefractive polymers: A novel class of chromophores (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 10637-10647 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is demonstrated that the microscopic mechanism of the photorefractive (PR) effect in organic composites with low glass transition temperatures involves the formation of refractive index gratings through a space-charge field-modulated Kerr effect. A tensorial formulation of the macroscopic aspects of the PR Kerr effect and its microscopic interpretation is presented. The second-order dipole orientation term containing the anisotropy of the first-order optical polarizability α(−ω;ω) is shown to yield the dominant contribution to the Kerr susceptibility χ(3)(−ω;ω,0,0). A class of special chromophores having negligible second-order polarizabilities β(−ω;ω,0) and large dipole moments μ has been identified in order to optimize this term. These chromophores are not subject to the efficiency-transparency tradeoff typically encountered with second-order nonlinear optical (NLO) chromophores, providing highly transparent materials with large PR Kerr response. Contrary to previous approaches in this field, the best-performing PR polymers are then expected to employ chromophores that would be useless for second- order applications (negligible β). We report PR of the material 30% 2,6-di-n-propyl-4H-pyran-4-ylidenemalononitrile (DPDCP): 15% N,N′-bis(3-methylphenyl)- N,N′-bis(phenyl)benzidine (TPD):55% poly(methyl methacrylate) (PMMA):0.3% C60 as an illustration of this principle. A 100 μm thick film of this material exhibits a steady-state diffraction efficiency of η=25% and net two-beam coupling of Γ=50 cm−1 at a bias field of 100 V/μm and a wavelength of 676 nm. The macroscopic Kerr susceptibility of the material is related to molecular electronic properties of the chromophore DPDCP which were independently determined by experiments in solution and by quantum chemical calculations. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472950
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  • 4
    Electronic Resource
    Electronic Resource
    Problems in the comparison of theoretical and experimental hyperpolarizabilities (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 7590-7599 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Frequently it is useful to compare experimental values of the hyperpolarizabilities β and γ with calculated values. It is also often helpful to compare experimental values of β obtained from dc-electric field induced second harmonic generation (dc-SHG) experiments, e.g., with values obtained using the solvatochromism method. In order to do this the hyperpolarizabilities must be defined using consistent conventions. In this paper, four commonly used conventions are discussed and simple factors for converting between them presented. In addition, the sum-over-states expression for the calculation of β and γ is described and its correct use in comparing with hyperpolarizabilities obtained using other experimental and theoretical techniques discussed. As an illustration of the consistent use of conventions, ab initio and semiempirical calculations on para-nitroaniline are compared with experimental dc-SHG values. This comparison highlights the difference between theoretical values of the hyperpolarizability with the molecule in a gas phase environment and experimental values obtained in polar solvents−a difference that has in the past been obscured by inconsistent choice of conventions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463479
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  • 5
    Electronic Resource
    Electronic Resource
    Holographische Methoden zur Untersuchung photochemischer und photophysikalischer Eigenschaften von Molekülen (1983)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 95 (1983), S. 612-629 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Holographie wird im allgemeinen als eine photographische Methode angesehen, mit der ein dreidimensionales Bild von einem Objekt erhalten werden kann. Dies ist sicherlich der spektakulärste Aspekt. Holographie kann jedoch auch als eine besonders leistungsfähige Methode zur Untersuchung einer Vielfalt von photochemischen und photophysikalischen Prozessen angewendet werden. Dabei stützen sich die experimentellen Techniken auf die Tatsache, daß das Hologramm, charakterisiert durch kleine räumliche Modulationen der optischen Eigenschaften (Brechungsindex und Absorptionskoeffizient) des Probenmaterials, einen einfallenden Lichtstrahl abzulenken vermag. Indem man die Zu- oder Abnahme der Intensität des abgelenkten Strahls beobachtet, lassen sich die Photoprozesse verfolgen, die die Änderungen der optischen Eigenschaften in der Probe hervorrufen. Wird zur Erzeugung des Hologramms ein kontinuierlicher Laser benutzt, so kann man photochemische Prozesse in Festkörpern untersuchen. Wird ein gepulster Laser verwendet, so können zeitabhängige Prozesse wie Energietransfer, Diffusion, Rotationsrelaxation, Ladungstransport etc. erfaßt werden. Gegenüber konventionellen spektroskopischen Methoden weisen die holographischen Techniken mehrere Vorteile auf, z. B. sind sie sehr empfindliche Nullmethoden und ermöglichen die freie Wahl von Wellenlänge sowie Intensität des Detektionsstrahls.  -  Aus den Ergebnissen der Anwendung der Holographie als photochemische und photophysikalische Untersuchungsmethode läßt sich durch Umkehrung der Fragestellung ein Zugang zu neuen Materialien für holographische Aufzeichnungen erschließen. Auf diese Weise ist es gelungen, die Zweiphotonen-Vierniveau-Systeme zu entwickeln, die als erste praktische Systeme für die Aufzeichnung von Hologrammen im IR-Bereich geeignet sind; in diesem Spektralbereich arbeiten die billigen und breit verwendbaren Diodenlaser. Die Zweiphotonen-Vierniveau-Materialien sind selbstentwickelnd, der Aufzeichnungsprozeß ist räumlich und zeitlich steuerbar (Gate-Prozeß), und das Lesen des Hologramms mit einem IR-Laserstrahl führt nicht zur Löschung der Information.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19830950805
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  • 6
    Electronic Resource
    Electronic Resource
    Holographic Methods for the Investigation of Photochemical and Photophysical Properties of Molecules (1983)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 22 (1983), S. 582-598 
    Details
    ISSN: 0570-0833
    Keywords: Analytical methods ; Holography ; Photochemistry ; Photophysics ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Holography is most frequently thought of as a method of photography that results in three-dimensional images of the object being photographed. It is certainly true that this is the most visually spectacular aspect. But holography can also be used as a powerful tool for the investigation of a variety of photochemical and photophysical processes. These experimental techniques rely on the fact that small spatial modulations of a material's optical properties (index of refraction and absorption coefficient) can deflect an incident light beam into another direction. By following the growth or decay in intensity of this deflected beam, one can follow the underlying photochemical and photophysical processes producing the changes in optical properties. If a CW laser is used to produce the hologram one can use the technique to investigate solid state photochemistry. If a pulsed laser is used one can investigate a broad range of time dependent processes; energy transfer, diffusion, rotational relaxation, charge transport etc. Compared to conventional spectroscopic techniques the holographic method shows various advantages. So for example it is a highly sensitive zero-background technique and permits free choice of detection wavelength and detection beam intensity.As a result of information obtained using the holographic technique as a scientific tool, one can also find new classes of materials for the recording of holograms. This is the way in which two-photon four-level systems for hologram recording process gated on and off with an auxiliary source, and can be read with the infrared recording laser with no erasing of the hologram.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.198305821
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