Quasielastic neutron scattering and microscopic dynamics of liquid ethylene glycol

Quasielastic neutron scattering (QENS) by liquid ethylene glycol was analyzed using different model approaches. It was found that approximation of the QENS spectra by a set of Lorentzian functions corresponding to the translational and rotational motions produce physically unrealistic results. At the same time, the Fourier transform of the stretched-exponential function exp(−(t/τ)β) fits the experimental data well, and results of the fit are in good agreement with those obtained earlier for other systems. The stretching parameter β was found Q independent and shows weak temperature dependence. The mean relaxation time as a function of Q departs strongly from the simple diffusion low and can be approximated by a power law 〈τw〉 = τ0Q−γ with the exponent parameter γ = 2.4.