Recovering molecular orientation from convoluted orbitals

Scanning probe microscopy lets us “see” atoms and molecules with unprecedented detail, particularly when the resolution is enhanced by functionalizing the tip of the microscope through deliberate adsorption of atomic or molecular species. However, interpreting the resultant images is often far from trivial as they contain features of both the tip and the sample. Here, a computationally simple theoretical approach is presented that allows the orientations of the tip and sample molecules to be determined from a single scanning tunneling microscopy (STM) image, which in turn reveals information on the bonding interaction between the molecules and the tip and surface. We use the approach to deconvolve the experimental STM images arising from the interaction between a C60-functionalized tip and a C60 molecule adsorbed on a Si(111)-(7 × 7) surface. The results provide experimental verification of the surface orientations postulated theoretically by Rurali et al.. [Phys. Rev. B 81, 075419 (2010)].