1. Institut für Physikalische
Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr. 30, D-48149 Münster,
Germany
2. Instituto de Física
de
São Carlos, Universidade de São Paulo (USP), C.P. 369, CEP 13560-970, São Carlos, SP, Brazil
3. Department of Materials Science and Engineering, Iowa State University of Science & Technology, 2200 Hoover Hall, Ames, Iowa 50010, United States