1. Dip. Fisica, Universitá
di Roma TRE, Roma, Italy and Institut D’Alembert Université
Pierre et Marie Curie case 162 4, place jussieu 75252 Paris Cedex
05
2. D’Appolonia SpA 00142, Roma, Italy
3. Inorganic Chemistry and Physical Chemistry Department, University of Food Technology, Maritza Blvd 26, 4000 Plovdiv, Bulgaria
4. IAC−CNR 00185, Roma, Italy
5. Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria