Observation of constant loss in fast relaxation spectra of polymers - art. no. 172004

Observation of the constant loss contribution to the light scattering spectra in GHz frequency range is presented. The constant loss appears as a frequency-independent imaginary part of the susceptibility spectrum. It shows a strong temperature variation. Analysis of the spectra and literature data suggests that the constant loss can be general for many glass-forming systems but it is hidden in many cases by other relaxation contributions. The nature of the constant loss is not clear. The possible mechanisms are discussed.