TERAHERTZ SPECTROSCOPY OF WATER IN INVERSE MICELLES

We report a study of the dielectric properties of water bound in inver se micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT), in heptan e, using terahertz time-domain spectroscopy. The size-dependent absorp tion and dispersion spectra of these nanometer-sized water pools are m easured in the spectral range 0.2-2 THz (6-60 cm(-1)), and are evaluat ed using a two-component Debye model. The amplitude of the dielectric relaxation in this spectral range is substantially smaller than that o bserved in bulk water. This is attributed to the effects of the confin ement, which disrupt the long-range collective modes normally present in the liquid. An additional higher frequency mode is observed, and it s potential origin discussed. (C) 1997 Published by Elsevier Science B .V.