Imaging and manipulation of a polar molecule on Ag(1 1 1)

A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(1 1 1) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could correspond to three distinct binding configurations. From a detailed analysis of the relative distance between neighboring three-lobed molecules we determine the adsorption site. Applying the lateral manipulation technique we demonstrate that the molecule can be pulled, slid or pushed by the tip on the surface. Accompanying with the reposition, molecular rotation and/or changing of binding configurations can also be induced. It is found that the dipole moment of the molecule has minor effects on its lateral movement. The results demonstrate that due to many degrees of freedom for large molecules, their manipulating processes can be much more complex in comparison with atoms and small molecules. Such information can shed light on the involved mechanisms on a molecular scale.