Is hydrated electron a good probe of the interior of reverse micelles?

Absorption spectra obtained after electron pulse irradiation to reverse micellar systems stabilized by nonionic surfactant, Brij30, or by mixture of anionic surfactant with nonionic one, i.e. AOT with Brij30, or by anionic surfactant AOT doped with polyethylene glycol, PEG35000 are presented. It is shown that excess electrons in such systems can be solvated in different environment, either in water core of reverse micelles or by hydrated molecules of Brij30 or PEG. Hence, neither system offers conditions enabling observation pure absorption spectrum of electron hydrated in small water droplet. Near infrared (1800-2100 nm) spectra of a combination mode of stretching and bending vibrations of water molecule allowed us to estimate the contribution of bulk-like water and quasi-monomeric water in dependence on reverse micellar system composition. They showed that Brij30 molecules take away water from micellar core more easily when nonpolar, continuous phase is made of n-heptane than, when it is made of decalin. (C) 2003 Elsevier Science Ltd. All rights reserved.