K W Hipps - Scanning Tunneling Microscopy and Orbital-Mediated Tunneling Spectroscopy of N,N′-Dioctyl-1,8:4,5-naphthalenediimide Adsorbed on Highly Ordered Pyrolytic Graphite from Various Solvents and in Different Environments

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      Publication Details (including relevant citation   information):

      Kleiner-Shuhler, Leslie, Brittain, Rebekah, Johnston, Martin R.,   Hipps, K. W. The Journal of Physical Chemistry C  2008 112 (38) 14907-14912

      Abstract: Scanning tunneling microscopy (STM)   and orbital-mediated tunneling spectroscopy (OMTS) are reported   for N,N′-dioctyl-1,8:4,5-naphthalenediimide (diimide) adsorbed on   highly ordered pyrolytic graphite (HOPG). The diimide forms well   ordered monolayers either at the interface between HOPG and   several phenylalkanes, or at the HOPG−air or HOPG−vacuum   interface when adsorbed from toluene. Planar adsorption of the   diimide ring on HOPG is observed. Hydrogen bonding, O and N   interaction with HOPG, and π−π interactions appear to be the   primary drivers for determining the monolayer structure which is   stable and independent of the adsorption method. This is an   unusual example since most alkane-substituted systems studied to   date rely on alkane chain interactions (with HOPG and   interdigitation) to drive the adsorbate structure on graphite.   The observed unit cell has a = 2.0 ± 0.2 nm, b = 1.95 ± 0.2 nm, α   = 67 ± 2°. The STM imaging is highly bias dependent and appears   to be controlled (in the ±2 V bias region) by an unoccupied   orbital. Orbital-mediated tunneling spectra reveal a single   strong electron affinity band near 3.5 eV below the vacuum level.

      Address (URL): http://dx.doi.org/10.1021/jp8039127