1. Department
of Environmental Science and Engineering, Ewha Womans University, Seoul 120-750, Korea
2. Department
of Physics, Central Michigan University, Mt. Pleasant, Michigan 48859, United States
3. School
of Mechanical Engineering, Yonsei University, Seoul 120-749, Korea
4. Department
of Applied Physics, College of Applied Science, Kyung Hee University, Yongin-si,
Giheung-gi, Gyeonggi-do 446-701, Korea
5. Institut
des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1-Ecole Nationale Supérieure de Chimie de Rennes, 11 allé de Beaulieu, CS 50837, F-35708 Rennes, France
6. Department
of Physics and Science of Advanced Materials Program, Central Michigan University, Mt.
Pleasant, Michigan 48859, United States