INTRODUCTION

According to the itinerant radical model [Muguet 92], [Muguet 96a], [Muguet 98b], the entity that is currently called a hydrated electron or (e-)aq should be understood instead as the mobile H3O. protic defect or itinerant hydronium radical. In a way similar to the F-center, also a neutral defect, the hydronium radical neutral defect moves under the influence of an electric field in the same direction as a negatively charged classical species. Similarly, in alcohols, the solvated electron (e-)solv should be understood as the itinerant alkyl-oxonium ROH2. radical. This conception would help to understand why the absorption spectrum of the solvated electron (e-)solv appears to depend on chemical properties, instead of physical properties such as the dielectric constant as predicted by the cavity model. Furthermore, Gordon Freeman discovered [Zhao 95] that the mobility of (e-)solv is closely related to the mobility of ROH- in various alcohols, a fact which is very hard to understand within the framework of the cavity model. Within the itinerant radical model, on the contrary, it is expected that mobilities of ROH- and ROH2. are related since both mobility mechanisms involve motion of itinerant protic defects. So far to our knowledge, the structures and dynamics of positive protic defects ie ROH2+ in liquid alcohols have been theoretically studied only in liquid methanol by Mark Tuckerman and coworkers [Morrone 02]. With the help of ab initio methods, it is not currently feasible to compute the absorption spectra of solvated alkyl-oxonium radicals. However we believe that the most important factor, that influences the absorption spectrum of various ROH2. radical, is their respective intramolecular structures. Therefore, our ultimate goal is to compute the absorption spectra of a significant number of isolated alkyl-oxonium radicals. Then, we expect that computed isolated alkyl-oxonium radical respective spectral shifts should match with observed respective spectral shifts between "solvated electrons" in various alcohols. As a first step towards determining of the absorption spectra of isolated ROH- in various alcohols in order to check the prediction of the itinerant radical model with experimental spectra, we have focused this study in determining the optimized geometries of the isolated ROH2+ alkyl-oxonium cations: CnH2n+1OH2+,n=1,2,3,4.

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