1. Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02-668 Warsaw, Poland
2. Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, PL-30-059 Krakow, Poland
3. Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
4. Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 2K6, Canada