[1] HARVARD UNIV, DEPT CHEM, CAMBRIDGE, MA 02138 USA
[2] LAB NAZL FRASCATI, INFN, I-00044 FRASCATI, ITALY
[3] UNIV CAMERINO, DIPARTIMENTO MATEMAT & FIS, I-62032 CAMERINO, ITALY
[4] UNIV AQUILA, DIPARTIMENTO FIS, I-67010 Coppito, ITALY
[5] STANFORD UNIV, STANFORD SYNCHROTRON RADIAT LAB, STANFORD, CA 94305 USA
[6] STANFORD UNIV, DEPT CHEM, STANFORD, CA 94305 USA