Affiliation: | a Institute of Physical Chemistry “I.G. Murgulescu”, Spl. Independentei no. 202, Sect. 6, Bucharest, Romania b Institute of Atomic Physics, National Institute for Materials Physics, P.O. Box MG-7, R-76900 Bucharest, Romania c Solid State Chemistry, University of Augsburg, Universitätstrasse 1, D-86159 Augsburg, Germany |