Volume 47, Number 1, July 1999
|Page(s)||56 - 62|
|Section||Condensed matter: structure, mechanical and thermal properties|
|Published online||01 September 2002|
The Raman coupling function in amorphous silica and the nature of the long-wavelength excitations in disordered systems
Università di Trento and Istituto Nazionale di Fisica della Materia I-38050, Povo, Trento, Italy
2 Università de L'Aquila and Istituto Nazionale di Fisica della Materia I-67100, L'Aquila, Italy
3 Università di Firenze and Istituto Nazionale di Fisica della Materia I-50139, Firenze, Italy
4 Institut für Festkörperforschung, Forschungszentrum Jülich Postfach 1913, D-52425, Jülich, Germany
Accepted: 21 April 1999
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 and, in particular, its low-frequency limit. This study indicates that in the limit extrapolates to a nonvanishing 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 nonregular local atomic displacements.
PACS: 63.50.+x – Vibrational states in disordered systems / 61.43.Fs – Glasses
© EDP Sciences, 1999
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