DOES THE INTERFACIAL POTENTIAL CONTROL THE CHARGE SEPARATION EFFICIENCY IN REVERSE MICELLAR MEDIA

The effect of the water pool size (omega degrees) on the average numbe r of the probe molecules located at the interface and on the monophoto nic ionization yield has been examined in anionic and cationic reverse micelles, using tetramethylbenzidine (TMB) as an easily photoionizabl e solute. The main conclusions of the present study are as follows: (1 ) The number of molecules located at the interface parallels that of t he square radius of the water pool and partly depends on the compactne ss of the interface. (2) Owing to the high concentration of the counte rions, the variations of the electrical potential remain low, when ome ga degrees increases from 18 to 40, although the fraction of free wate r increases significantly. (3) The charge separation efficiency (Y-TMB +) varies as the fraction of free water in the water pool. Such Y-TMB variations are interpreted in changes in the fundamental energy of th e excess electron at the interface with omega degrees. (4) The compari son of Y-TMB+ values, obtained in the present work with previous data in direct micelles, points out the influence of the sign of the curvat ure radius on the photoionization reaction.