1. J. R. Macdonald
Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506, United States
2. State
Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
3. Department
of Chemistry, University of Liege, B-4000 Liege, Belgium
4. The MOE Key Laboratory
of Weak-Light Nonlinear Photonics, TEDA Applied Physics
Institute and School of Physics, Nankai University, Tianjin 300457, China
5. Department
of Physics, Ludwig-Maximilians-Universität Munich, D-85748 Garching, Germany