Hyper-Raman scattering from vitreous boron oxide: coherent enhancement of the boson peak.
Hyper-Raman scattering spectra of vitreous B(2)O(3) are compared to Raman scattering ones. Particular attention is given to the low-frequency boson peak which relates to out-of-plane rigid librations of planar structural units, mostly boroxols. While the Raman strength can be accounted for by the motions of single units, the hyper-Raman signal exhibits a unequaled enhancement due to coherent librations of several boroxols. This important distinction is explained by the different symmetry properties of the polarizability and hyperpolarizability tensors of the structural units.
Simon
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G
Laboratoire des Colloïdes, Verres et Nanomatériaux, LCVN, UMR 5587 CNRS, University of Montpellier II, F-34095 Montpellier, France.
Hehlen
B
B
Courtens
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E
Longueteau
E
E
Vacher
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R