Fig. 3.

Imaginary component ϵ^″(ω) of the measured complex permittivity as a function of the angular frequency ω, at three temperatures, (A) T = 186 K, (B) T = 215 K, and (C) T = 245 K. Solid lines through the symbols are the result of the fitting procedure in the complex plane (see Methods and SI Text). Here, we show the results of the decomposition into two processes of the broad relaxation peak. Dashed lines represent the side-chain relaxation, and thick solid lines represents the proton relaxation. The fitting procedure yields a β₁ ≈ 1 (see Eq. 6) for the side-chain relaxation over the entire temperature range investigated, resulting in a symmetric relaxation process. Conversely, the same procedure gives a β₂ < 1 for the proton relaxation, resulting in a characteristic asymmetric shape. We omit for clarity the contributions due to sample conductivity and to electrode polarization at low frequency.