[1] Univ Cattolica, Dipartimento Matemat & Fis, I-25121 Brescia, Italy
[2] Univ Pavia, Dipartimento Fis A Volta, CNISM, I-27100 Pavia, Italy
[3] Univ Pavia, Dipartimento Chim, I-27100 Pavia, Italy
[4] IOM CNR, Lab TASC, I-34149 Basovizza, Italy
[5] Sincrotrone Trieste, I-34149 Basovizza, Italy