Ion transport in micelle-like films: Soft-landed ion studies

Ion-transport processes across epitaxially grown micelle-like films in the form of liquid hydrocarbon/water/hydrocarbon sandwiches were studied by a novel ion soft-landing technique. Centered inside of vapor-deposited glassy films of 3-methylpentane (166 monolayers) and methylcyclohexane (50 monolayers) was a water layer from 0 to 10 monolayers thick. From 90 to 150 K we time-resolved hydronium ion motion and found that the ions (D3O+)clearly paused in the aqueous phase, being transiently trapped by solvation interactions. A modified Born solvation model qualitatively showed that a trap energy gradually built up in the aqueous phase with the water layer thickness.