title: Vibrational excitation in single-molecule transistors: deviation from the simple franck-condon prediction.
abstract: We investigated the inner-sphere reorganization of ferrocene ((Cp) 2Fe ( n+ )) and tris(2,2'-bipyridine) iron ((bpy) 3Fe ( n+ )) in a single-molecule-transistor geometry. In (Cp) 2Fe ( n+ ) ( n = 0 and 1), almost no vibrations were excited during single-electron transport, whereas in (bpy) 3Fe ( n+ ) ( n = 1, 2, and 3), many distinct vibrations appeared, consistent with its larger reorganization energy. The observed excitation intensities varied significantly across devices, however, and could not be accounted for by "Franck-Condon" factors. This observation indicates that a quantitative account of electron-vibration coupling in single-electron tunneling requires further investigation.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: Nathalie P
authors.initials: NP
authors.lastname: de Leon
authors.forename: Wenjie
authors.initials: W
authors.lastname: Liang
authors.forename: Qian
authors.initials: Q
authors.lastname: Gu
authors.forename: Hongkun
authors.initials: H
authors.lastname: Park