Characterization and identification of the nature of two different kinds of secondary relaxation in one glass-former

Dielectric measurements were carried out in the van der Waals liquid di-n-octyl phthalate at ambient pressure. Two secondary relaxation processes were found in the dielectric spectra, namely, an excess wing and a γ-process at higher frequencies. It has been established that the excess wing is the universal JG relaxation. Moreover we pointed out that γ-relaxation times show a minimum in temperature dependence. A Minimal Model proposed by Dyre and Olsen was successfully applied to explain this unusual behaviour of the γ-relaxation in di-n-octyl phthalate.