Europhys. Lett., 64 (5) , pp. 675-681 (2003)
Confinement effects on the excess wing in the dielectric loss of glass-formersR. Bergman, J. Mattsson, C. Svanberg, G. A. Schwartz and J. Swenson
Department of Applied Physics, Chalmers University of Technology SE-412 96 Göteborg, Sweden email@example.com
(Received 28 February 2003; accepted in final form 16 September 2003)
We present results from dielectric spectroscopy on four molecular glass-formers, both in bulk and in confined geometry. For systems exhibiting a well-resolved secondary ( ) relaxation, the confinement induces a relative enhancement (compared to the main relaxation) of the effective dielectric strength of the process. In bulk systems without a well-separated process a similar relative enhancement is found also for the contribution to the dielectric loss identified as the excess wing. The latter effect results in a bimodal loss, which suggests that the excess wing should be attributed to a relaxation process separate from, and thus not a feature of, the relaxation. The results hence provide an explanation for the much debated excess wing often observed in the dielectric response of glass-formers.
64.70.Pf - Glass transitions.
77.22.Gm - Dielectric loss and relaxation.
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