1. National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
2. The Ohio State University, Columbus, Ohio 43210, USA
3. Department of Chemistry, Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, N-0316 Oslo, Norway
4. Department of Physics, University of Oslo, N-0316 Oslo, Norway