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(107) Production(s) de FORET M.
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Vibrational modes and local order in permanently densified silica glasses: Femtosecond and Raman spectroscopy study 
Auteur(s): Burgin J., Guillon C., Langot P., Vallée F., Hehlen B., Foret M.
(Article) Publié:
Physical Review B, vol. 78 p.184203 (2008)
Ref HAL: hal-00339618_v1
DOI: 10.1103/PhysRevB.78.184203
WoS: 000261214800040
Exporter : BibTex | endNote
32 Citations
Résumé: The D1 and D2 vibrational ring modes of normal and densified silica are investigated using a time resolved pump-probe technique and spontaneous Raman spectroscopy. The vibrational response function of both techniques is derived and compared to the experimental results obtained on three samples of silica of increasing density. Comparison of the amplitudes of the time- and frequency-domain responses reveals a much larger increase in concentration of three-membered rings as compared to four-membered ones upon densification. In addition, measurements of the Raman-scattering intensity in SiO2 also provide a mean to identify bending motions and to estimate the variation of the average Si-O-Si bond angle in densified samples.
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Hypersound Damping in Vitreous Silica Measured by Picosecond Acoustics
Auteur(s): Devos A., Foret M., Ayrinhac Simon, Emery P., Ruffle B.
(Article) Publié:
Physical Review B, vol. 77 p.100201(R) (2008)
Ref HAL: hal-00512645_v1
Exporter : BibTex | endNote
Résumé: The attenuation of longitudinal acoustic phonons up to frequencies nearing 250 GHz is measured in vitreous silica with a picosecond optical technique. By taking advantage of interferences on the probe beam, difficulties encountered in early pioneering experiments are alleviated. Sound damping at 250 GHz and room temperature is consistent with relaxation dominated by anharmonic interactions with the thermal bath, extending optical Brillouin scattering data. Our result is at variance with claims of a recent deep-UV experiment which reported a rapid damping increase beyond 100 GHz. A comprehensive picture of the frequency dependence of sound attenuation in nu-SiO2 can be proposed.
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Hypersound Damping in Vitreous Silica Measured by Picosecond Acoustics
Auteur(s): Foret M.
Conference: XI e International Wokshop on Complex Systems (Andalo, Italie, FR, 2008-03-16)
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Elasticity and anelasticity of oxide glasses
Auteur(s): Courtens E., Foret M., Ruffle B., Vacher R.
(Article) Publié:
European Journal Of Glass Science And Technology: Part B - Physics And Chemistry Of Glasses, vol. 48 p.9-18 (2007)
Ref HAL: hal-00512649_v1
Exporter : BibTex | endNote
Résumé: The current understanding of sound properties in glasses is reviewed and compared to that in crystals. Sound damping in oxide glasses is controlled mainly by three processes which in increasing order of the frequency at which they dominate are: the thermal relaxation of defects, relaxation via anharmonic interactions with the thermal bath, and hybridization with optic-like vibrations. The former two also affect distinctly the velocity of sound. The latter one relates to the boson peak and the low temperature plateau generally observed in the thermal conductivity. In addition, in silica and other tetrahedrally coordinated glasses, the sound velocity tends to increase with temperature, presumably owing to a progressive structural change.
Commentaires: 0031-9090
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High Frequency Brillouin Scattering : a clue to understanding thermodynamic anomalies of glasses
Auteur(s): Foret M., Ruffle B., Hehlen B., Courtens E., Vacher R.
Conference: XXI International Congress on Glass (Strasbourg, France, FR, 2007-07-01)
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