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The Raman coupling function in amorphous silica and the nature of the long wavelength excitations in disordered systems

A. Fontana·R. Dell'Anna·M. Montagna·F. Rossi·G. Viliani·G. Ruocco·M. Sampoli·U. Buchenau·A. Wischnewski
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Abstract

New Raman and incoherent neutron scattering data at various temperatures and molecular dynamic simulations in amorphous silica, are compared to obtain the Raman coupling coefficient $C(ω)$ and, in particular, its low frequency limit. This study indicates that in the $ω\to 0$ limit $C(ω)$ extrapolates to a non vanishing value, giving important indications on the characteristics of the vibrational modes in disordered materials; in particular our results indicate that even in the limit of very long wavelength the local disorder implies non-regular local atomic displacements.

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A. Fontana, R. Dell'Anna, M. Montagna, F. Rossi, G. Viliani, G. Ruocco, M. Sampoli, U. Buchenau, A. Wischnewski. 1999-11-16. The Raman coupling function in amorphous silica and the nature of the long wavelength excitations in disordered systems. https://doi.org/10.1209/epl%2Fi1999-00351-x

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