title: Charge localization in isolated mixed-valence complexes: an STM and theoretical study.
abstract: {Cp*(dppe)Fe(C≡C-)}(2)(1,3-C(6)H(4)) is studied both as a neutral molecule, Fe(II)-Fe(II), and as a mixed-valence complex, Fe(II)-Fe(III). Scanning tunneling microscopy (STM) is used to image these species at 77 K under ultrahigh-vacuum conditions. The neutral molecule Fe(II)-Fe(II) has a symmetric, "dumbbell" appearance in STM images, while the mixed-valence complex Fe(II)-Fe(III) demonstrates an asymmetric, bright-dim double-dot structure. This asymmetry results from localization of the electron to one of the iron-ligand centers, a result which is confirmed through comparison to theoretical STM images calculated using constrained density-functional theory (CDFT). The observation of charge localization in mixed-valence complexes outside of the solution environment opens up new avenues for the control and patterning of charge on surfaces, with potential applications in smart materials and molecular electronic devices.
authors.affiliation: Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Lu
authors.forename: Rebecca
authors.initials: R
authors.lastname: Quardokus
authors.forename: Craig S
authors.initials: CS
authors.lastname: Lent
authors.forename: Frederic
authors.initials: F
authors.lastname: Justaud
authors.forename: Claude
authors.initials: C
authors.lastname: Lapinte
authors.forename: S Alex
authors.initials: SA
authors.lastname: Kandel