Density dependence of the boson peak of vitreous silica

Density dependence of low-energy dynamics of vitreous silica was investigated by means of neutron scattering measurements. On densification, the intensity of the boson peak is drastically suppressed at the low-energy region, and eventually its position shifts toward higher energy. From this result we conclude that the origin of the boson peak is not a phonon scattering by local density fluctuations but a soft mode of void space in vitreous silica. (C) 2000 Published by Elsevier Science B.V. All rights reserved