1. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, F. Skaryna Ave. 70, Minsk 220072, Belarus; Laboratory of Molecular Physics, Department of Biomolecular Sciences, Agricultural University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands, and A. V. Bogatsky Physico-Chemical Institute, National Academy of Sciences of Ukraine, Lustdorfskaya doroga 86, 270080, Odessa, Ukraine