Dielectric Behaviour and Molecular Motion in Low-Temperature Phase of t-Nitrobutane (TBN)

Low-temperature phase transition at 215 K in t-nitrobutane is accompanied by considerable jump of electric permittivity. Measurements of ϵ*(T) in microwave region and calculated correlation functions, by using additionally data on α(ω) in far infra-red, allow to conclude that the permittivity jump is due to the change of the potential energy shape for librations perpendicular to the polar axis of molecules. It has been shown that dielectric losses can be ascribed to the low-frequency wing of the absorption band which during phase transition is shifted towards higher frequencies.