[1] UNIV PENN, DEPT CHEM, PHILADELPHIA, PA 19104 USA
[2] UNIV PENN, RES STRUCT MATTER LAB, PHILADELPHIA, PA 19104 USA
[3] UNIV FLORENCE, DIPARTIMENTO CHIM, SPETTROSCOPIA MOLEC LAB, I-50121 FLORENCE, ITALY
[4] EUROPEAN LAB NONLINEAR SPECT, I-50124 FLORENCE, ITALY