title: Iron wheels on silicon: wetting behavior and electronic structure of adsorbed organostannoxane clusters.
abstract: Atomic force microscopy and synchrotron radiation (SR) spectroscopy have been used to study the wetting behavior and electronic structure of thin films of a novel organometallic cluster--[BuSn(O)OC(O)Fc]6 ("Fc" = ferrocenyl)--on silicon substrates. This cluster comprises six ferrocene units connected to a stannoxane central core--"an iron wheel on a tin drum" (V. Chandrasekhar; et al. Angew. Chem., Int. Ed. 2000, 39, 1833). Thin films spin-cast onto native oxide-terminated silicon readily dewet the substrate. We have utilized advanced image analysis techniques based on Minkowski functionals to provide a detailed quantitative analysis of the morphology of the stannoxane overlayers. This analysis shows that the dewetting patterns are rather far removed from those expected to arise from a simple Poisson distribution of centers, and we discuss the implications of this finding in terms of nucleated and spinodal dewetting. Variations in both the surface roughness and the in-plane correlation length have been followed as a function of annealing time to probe the surface dewetting dynamics. SR valence band photoemission illustrates that the highest occupied molecular orbital (HOMO) of the cluster is found 2 eV below the Fermi level. Fe 2p --> 3d and Sn 3d --> 5p resonant photoemission spectroscopy have been used to enhance the cross sections of the partial density of states associated with the Fe and Sn atoms. Sn atoms make a large contribution to the HOMO of the cluster, whereas the Fe atoms are associated with an electronic environment seemingly very similar to that in the "parent" ferrocene molecule.
authors.affiliation: National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: F
authors.initials: F
authors.lastname: Frehill
authors.forename: K H G
authors.initials: KH
authors.lastname: Schulte
authors.forename: C P
authors.initials: CP
authors.lastname: Martin
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.forename: J A
authors.initials: JA
authors.lastname: Purton
authors.forename: J G
authors.initials: JG
authors.lastname: Vos
authors.forename: P
authors.initials: P
authors.lastname: Moriarty