RESUMO
We study the changes in the low-frequency vibrational dynamics of poly(isobutylene) under pressure up to 1.4 GPa, corresponding to a density change of 20%. Combining inelastic neutron, x-ray, and Brillouin light scattering, we analyze the variations in the boson peak, transverse and longitudinal sound velocities, and the Debye level under pressure. We find that the boson peak variation under pressure cannot be explained by the elastic continuum transformation only. Surprisingly, the shape of the boson peak remains unchanged even at such high compression.
RESUMO
We report unexpectedly strong variations in the quasielastic scattering (QES) intensity in glasses under pressure. Analysis of the data reveals strong correlations between pressure-induced changes in the QES intensity and the intensity of the boson peak. This observation emphasizes a direct relationship between these two components of the fast dynamics. In addition, we observe changes of the QES spectral shape that can be interpreted as pressure-induced variations in the underlying energy landscape.