  The electronic structure of ZnPc, from sub-monolayers to thick films, on bare
and iodated Pt(111) is studied by means of X-ray photoelectron spectroscopy
(XPS), X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy
(STM). Our results suggest that at low coverage ZnPc lies almost parallel to
the Pt(111) substrate, in a non-planar configuration induced by Zn-Pt
attraction, leading to an inhomogeneous charge distribution within the molecule
and charge transfer to the molecule. ZnPc does not form a complete monolayer on
the Pt surface, due to a surface-mediated intermolecular repulsion. At higher
coverage ZnPc adopts a tilted geometry, due to a reduced molecule-substrate
interaction. Our photoemission results illustrate that ZnPc is practically
decoupled from Pt, already from the second layer. Pre-deposition of iodine on
Pt hinders the Zn-Pt attraction, leading to a non-distorted first layer ZnPc in
contact with Pt(111)-I $\left(\sqrt{3}\times\sqrt{3}\right)$ or Pt(111)-I
$\left(\sqrt{7}\times\sqrt{7}\right)$, and a more homogeneous charge
distribution and charge transfer at the interface. On increased ZnPc thickness
iodine is dissolved in the organic film where it acts as an electron acceptor
dopant.
