1. Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador Sãocarlense 400, São Carlos, SP 13566-590, Brazil
2. Science and Technology Division, Corning Incorporated, Corning, New York 14831, United States
3. Institut für Physikalische Chemie, WWU Münster, Corrensstraße 28-30, 48149 Münster, Germany