Affiliation: | 1. TU Freiberg, Institute of Theoretical Physics, Leipziger Str. 23, D-09599 Freiberg, Germany;2. Department of Physics, Central Michigan University, Mount Pleasant, Michigan, 48859;3. TU Freiberg, Institute of Theoretical Physics, Leipziger Str. 23, D-09599 Freiberg, Germany Freiberg Instruments GmbH, Delfter Str.6, D-09599 Freiberg, Germany |