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  • 1
    Electronic Resource
    Electronic Resource
    Low-frequency Raman scattering and structure of amorphous polymers: Stretching effect (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 2949-2954 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Low-frequency Raman scattering of amorphous polymers [polyethyleneterephthalate (PET) and polymethylmethacrylate] is investigated. The low-frequency Raman band called "Boson peak'' is interpreted in terms of a noncontinuous structure, similar to that of inorganic glasses, i.e., solid amorphous polymers are composed of 50 A(ring) blobs. These are related blobs to transient entanglements in the polymer melt. Modifications induced by stretching are described for a PET film. The nature of the blob structure is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460896
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamical structure of water: Low-frequency Raman scattering from a disordered network and aggregates (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2150-2154 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Low-frequency inelastic light scattering of water is observed from a temperature equal to 80 down to −20 °C in the supercooled regime. For energies higher than 3 cm−1 it is shown that the major part of the light scattering is Raman scattering. A broadband with a maximum at 50 cm−1 is interpreted as scattering from transverse acoustic modes of a disordered network. A weaker scattering which shifts towards the Rayleigh line when the temperature decreases is well explained by Raman scattering from the oscillations of water molecule aggregates which grow when the temperature decreases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458006
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  • 3
    Electronic Resource
    Electronic Resource
    Nanocrystallites vibration modes of CdSxSe1−x semiconductors in glasses: Size determination by Raman scattering (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 5237-5239 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nanocrystallites eigenmodes of CdSxSe1−x semiconductors are observed by low frequency inelastic scattering and the diameters ranging between 2.5 nm and 9 nm are determined. This new application of Raman scattering is a powerful tool to study quantum size effects in these nonlinear optical materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460529
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  • 4
    Electronic Resource
    Electronic Resource
    Correlation effects on Raman scattering from low-energy vibrational modes in glasses. II. Experimental results (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2046-2051 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: New experimental results of low-frequency Raman scattering from different glasses are presented. They are compared to the vibration density of states obtained from inelastic neutron scattering to deduce the light-vibration coupling coefficient C(ω) as a function of the vibration frequency. It was found that C(ω)∝ω2 at very low frequency ω〈20 cm−1 in inorganic glasses (SiO2,B2O3) and that C(ω)∝ω at low frequency in polymer glasses and in inorganic glasses for ω(approximately-greater-than)20 cm−1. Our experimental results for glasses are interpreted by assuming no correlation at very low-frequency and only radial correlation at low-frequency. A full correlation would exist in silica-aerogels in which the effect of random fluctuations would be negligible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465268
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  • 5
    Electronic Resource
    Electronic Resource
    Correlation effects on Raman scattering from low-energy vibrational modes in fractal and disordered systems. I. Theory (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2040-2045 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In disordered fractal or nonfractal systems, the disorder induces rapid fluctuations of the acoustical vibrational wave functions, so that statistics can be used to resolve the problem of Raman scattering from localized low-energy vibrations. We derive the expressions of light-vibration coupling coefficient, C(ω), as a function of the frequency ω, in the case of the dipole-induced dipole mechanism of susceptibility fluctuation and for different types of correlation, from full correlation to no-correlation. The results are compared to the existing numerical calculations. The expressions of C(ω) are determined for other mechanisms of susceptibility fluctuations, depending on an interaction propagating in the fractal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465267
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  • 6
    Electronic Resource
    Electronic Resource
    Dependence of quasielastic light scattering in poly(methyl methacrylate) on the concentration of free monomers (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 6818-6821 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The quasielastic light scattering (QELS) of poly(methyl methacrylate) was measured as a function of both temperature and free monomer concentration, which was varied by heating. The motion responsible for the QELS is not thermally activated (i.e., the corresponding relaxation time is independent of temperature), while the QELS intensity is strongly temperature dependent and proportional to the monomer concentration. The QELS is interpreted as due to a rapid localized motion released by thermally activated slow structural relaxation, which can create free volume. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471348
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  • 7
    Electronic Resource
    Electronic Resource
    A model of low-frequency Raman scattering in glasses: Comparison of Brillouin and Raman data (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 4691-4698 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A model of the low-frequency Raman scattering intensity in glasses is proposed, which describes the spectrum in the region of the boson peak, typical of glasses. The model considers the boson peak as a result of first-order light scattering by harmonic quasilocalized vibrations. The amplitude, frequency, and polarization dependence of the light on the vibrational coupling coefficient C(ω) are estimated. The model predicts a linear frequency dependence of C(ω) in the region of the boson peak and the depolarization ratio as a function of the relative contribution of the longitudinal and transverse-type motions which comprise these quasilocal vibrational modes. Low-frequency Raman and Brillouin measurements have been made on SiO2 glass in order to check the predictions of the model regarding the amplitude and integrated intensity of the boson peak. The estimated ratio of these values to those of the Brillouin lines are in good agreement with experiment. Comparison of the theoretical and experimental values of the depolarization ratio for the boson peak shows a predominance of the transverse-type atomic motions in the low-frequency quasilocalized vibrational modes in glasses. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469517
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  • 8
    Electronic Resource
    Electronic Resource
    Low-energy excitations in glass-forming aqueous lithium–chloride (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 8114-8117 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Low frequency Raman and inelastic neutron scattering from glass-forming aqueous lithium chloride (LiCl,4H2O; LiCl,6H2O) are compared. The measurements were carried out from the vitreous to liquid states. The scattering from anharmonic oscillations (light scattering excess), which was separated from the one from harmonic vibrations, is zero in the vitreous state, and increases rapidly in the supercooled state. The frequency dependence of light-vibration coupling coefficient is linear for low-energy harmonic vibrations. It is different for anharmonic oscillations. From the frequency dependence of the density of vibrational states and the absence of light scattering excess in the glassy state, it is deduced that the structure is compact in the glassy state. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469221
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  • 9
    Electronic Resource
    Electronic Resource
    Resonant Raman scattering by breathing modes of metal nanoparticles (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 3444-3447 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Low-frequency Raman scattering experiments have been performed on metal nanoparticles embedded in two different thermally treated matrices. In addition to the well-known Raman scattering by the nanoparticle quadrupolar vibrational mode, the spectra measured in the 3–40 cm−1 frequency range exhibit several new bands. They are ascribed to resonant scattering by the nanoparticle breathing mode and its harmonics, in very good agreement with time-resolved measurements. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1396817
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  • 10
    Electronic Resource
    Electronic Resource
    ^2T"1 pumping of the R lines in ruby
    Amsterdam : Elsevier
    Physics Letters A 93 (1983), S. 241-244 
    Details
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0375-9601(83)90807-1
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