Brillouin neutron scattering of -L. E. Bove1, E. Fabiani2, A. Fontana1, 3, F. Paoletti4, C. Petrillo1, 4, O. Pilla3 and I. C. V. Bento5
1 INFM CRS-SOFT, c/o Università di Roma "La Sapienza" - I-00185 Roma, Italy
2 Institut Laue Langevin - BP 156, Grenoble, France
3 Dipartimento di Fisica, Università di Trento - I-38050 Povo (Trento), Italy
4 Dipartimento di Fisica, Università di Perugia - Perugia, Italy
5 Departamento de Física, Universidade Federal do Ceará CP 6030, Campus do Pici, 60455-760 Fortaleza, Ceará, Brazil
received 22 February 2005; accepted in final form 21 June 2005
published online 20 July 2005
The high-frequency dynamics of - was investigated by inelastic neutron scattering. Neutron experiments were carried out by exploiting both three-axis and time-of-flight techniques as most adequate to selectively access to a wider kinematics region or to higher-resolution characteristics. Experimental evidences of a highly dispersing inelastic peak, with an associated velocity of 3650 , and an almost dispersionless inelastic structure allowed us to definitely confirm the propagating nature of the high-frequency excitations. The measured data were compared with the results of a molecular-dynamics simulation.
42.70.Ce - Glasses, quartz.
25.40.Fq - Inelastic neutron scattering.
73.43.Lp - Collective excitations.
© EDP Sciences 2005