Light scattering and dielectric manifestations of secondary relaxations in molecular glassformers
Photon correlation data of the molecular glass-forming materials 2-picoline, dimethylphthalate (DMP) and salol are compared with their dielectric loss spectra in the time-frequency range where the dielectric data reveal secondary relaxations. Slow secondary relaxation processes in molecular liquids are commonly studied by dielectric spectroscopy (DS) and, based on such studies, believed to be characteristics of the deeply super-cooled liquid state. However, there has been no direct experimental evidence that they are similarly detected by other experimental techniques. In the present study, we experimentally address this question for the anisotropic (depolarized) light scattering (LS). In the first approximation, DS and LS probe the same molecular reorientation dynamics, and therefore are expected to provide qualitatively similar spectra. We find however that this is not the case, namely i) the magnitude of the slow secondary relaxations is much less in LS than in DS data, which is the opposite to expectations; ii) the shape of the relaxation spectrum is qualitatively different, concerning both the main and secondary processes. We discuss possible sources of these differences in the context of related data from the literature. Copyright Springer-Verlag Berlin/Heidelberg 2003
Year of publication: |
2003
|
---|---|
Authors: | Brodin, A. ; Bergman, R. ; Mattsson, J. ; Rössler, E. |
Published in: |
The European Physical Journal B - Condensed Matter and Complex Systems. - Springer. - Vol. 36.2003, 3, p. 349-357
|
Publisher: |
Springer |
Saved in:
Online Resource
Saved in favorites
Similar items by person
-
Depolarized light scattering study of glycerol
Brodin, A., (2005)
-
Dynamical phase transition in simple supercooled liquids and polymers - an NMR approach
Rössler, E., (1993)
-
Relaxational and vibrational contributions to the dynamics of the glass transition
Sokolov, A.P., (1993)
- More ...