Coherent Neutron Scattering from the Ionic Mixture of Ethylammonium Nitrate and Deuterated n-Octanol in the Critical Region
Neutron scattering measurements were performed on the ionic mixture of ethylammonium nitrate and deuterated n-octanol in order to get information about its microscopic structure in the vicinity of the critical point. Scattering spectra were recorded for momentum transfers q, ranging from 0.06 to 0.46 Å−1. A sample at the critical salt mole fraction X c = 0.760, was studied in its homogeneous phase at various temperatures between (T c + 0.93)°C and (T c + 24.12)°C, where T c is the critical temperature. This corresponds to reduced temperatures τ = (T− T c)/Tc, in the range 3.1 × 10−3≤τ≤8.0 × 10−2. The spectra of the coherent intensity scattered from the critical mixture are described well by the Fisher-Langer approximation in a wide range of qξ values, ξ being the critical correlation length. However, at least one additional shorter characteristic length is needed for a proper description of the spectra over the whole range of q.
Keywordscritical-point phenomena ionic mixtures neutron scattering
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