Comment on "Merging of and slow relaxation in supercooled liquids".
Fujima [T. Fujima, H. Frusawa, and K. Ito, Phys. Rev. E 66, 031503 (2002)] report on broadband dielectric relaxation measurements on two glass-formers. They find that the relaxation times of the beta relaxation follow different temperature dependences above and below the glass-transition temperature, Tg; i.e., there appears to be a crossover at Tg where the activation energy of the beta relaxation change. In this Comment we show that the observed behavior can be explained by analyzing the merging of the alpha and beta relaxations using an approach proposed by Williams. This analysis clearly shows that the low temperature (below Tg) behaviors of the alpha and beta relaxations can be used to describe also the high-temperature behavior (above Tg). The apparent change in activation energy is thus not to be identified with a change in relaxation mechanism.
Bergman
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Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden. f5xrb@fy.chalmers.se
Svanberg
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