Dynamics of water confined within reverse micelles

We report structural and dynamical properties of water confined within reverse micelles ( RMs) ranging in size from R = 10 angstrom to R = 23 angstrom as determined from molecular dynamics simulations. The low- frequency infrared spectra have been calculated using linear response theory and depend linearly on the fraction of bulklike water within the RMs. Furthermore, these spectra show nearly isosbestic behavior in the region near 660 cm(-1). Both of these characteristics are present in previously measured experimental spectra. The single dipole spectra for interfacial trapped, bound, and bulklike water within the RMs have also been calculated and show region- dependent frequency shifts. Specifically, the bound and trapped water spectra have a peak at lower frequencies than that for the inner core water. We therefore assign the low- frequency band in the IR spectra to bound and trapped interfacial water. Finally, region- dependent hydrogen bonding profiles and spatial distribution functions are also presented.