1. CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Université Aix-Marseille III, Europole Méditerranéen de l'Arbois, BP80, 13545 Aix en Provence Cedex 4, France, and Departments of Environmental Science and Engineering, Chemical Engineering, Chemistry, and Mechanical Engineering and Materials Science, Rice University, 6100 Main Street, Houston, Texas 77005-1892