ULTRAFAST ELECTRON-DIFFRACTION - STRUCTURES IN DISSOCIATION DYNAMICS OF FE(CO)(5)

We report on the application of ultrafast electron diffraction (UED) t o the study of complex molecular reactions, the dissociation of Fe(CO) (5). Snapshots of the diffraction images were recorded at different re action times. The reaction was initiated by a femtosecond pulse and cl ocked accurately within 2 ps. The dissociation is complete in less tha n 10 ps and we identify major product distributions and structures; Fe (CO)(2), Fe(CO) and Fe in the branching ratio of ca. 2:5:5. The C-O di stance becomes longer, relative to that of Fe(CO)(5), suggesting a non -systematic weaker C-O bond in Fe(CO)(2) and Fe(CO) fragments. The tem poral diffraction-difference method greatly enhances the ability of re cording structural changes in UED. (C) 1997 Elsevier Science B.V.