In situ electrochemical–ellipsometry studies of charge-transfer processes at the liquid/liquid interface
Abstract
In
situ ellipsometry has been used to characterise the properties of the interface between 1,2-dichloroethane (containing tetrabutylammonium hexafluorophosphate) and water (containing lithium sulfate)
during electrochemical potential step (chronoamperometry) experiments with a four-electrode potentiostat.
The ellipsometry behaviour was analysed according to changes in the real Δ(rr) and imaginary Δ(ri) signals
measured at the Brewster angle during polarisation of the interface between two immiscible electrolyte
solutions (ITIES). It was found that both the Δ(rr) and Δ(ri) responses represented relatively slow changes
through the interface profile that scaled reversibly with the sign and magnitude of the potential jumps.
The ellipsometry responses provided spectroscopic evidence of ion-transfer and accumulation processes ia
measurement
of changes in the refractive index and variation of the dielectric constant in the interface region.
The spectroscopic data were consistent with previous models that indicate
the ITIES is
composed of a mixed solvent layer
with varying penetration
of electrolyte ion pairs.