K W Hipps - Scanning Tunneling Microscopy and Orbital-Mediated Tunneling Spectroscopy Study of 1,5-Di(octyloxy)anthracene Adsorbed on Highly Ordered Pyrolytic Graphite from Various Solvents and in Different Environments

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  Publication Details (including relevant citation   information):

  Pokrifchak, Matthew, Turner, Tracey, Pilgrim, Ian, Johnston,   Martin R., Hipps, K. W. The Journal of Physical Chemistry   C 2007 111 (21) 7735-7740

  Abstract: Scanning tunneling microscopy (STM)   and orbital mediated tunneling spectroscopy (OMTS) are reported   for 1,5-di(octyloxy)anthracene (15DA) adsorbed on highly ordered   pyrolytic graphite (HOPG). 15DA forms well-ordered monolayers   either at the interface between HOPG and 1-phenyloctane or at the   HOPG−air or HOPG−vacuum interface when spin doped from octane or   dichloromethane. Octyl chain interdigitation and planar   adsorption of the anthracene ring combine to produce structures   which are stable independent of the adsorption method. The   observed unit cell has a = 1.76 ± 0.06 nm, b = 1.07 ± 0.06 nm,   and α = 77 ± 3°. Molecular orbital calculations are combined with   bias-dependent imaging and OMTS results to show that the   highest-occupied molecular orbital (****) dominates the tunneling   process over the voltage range from −2.5 to +1.0 V. The **** of   15DA on HOPG is found to occur at −7.0 eV below the vacuum level,   in good agreement with previous UPS studies and with our   calculations for the free molecule. We also report the first   synthesis of 15DA.

  Address (URL): http://dx.doi.org/10.1021/jp0704968