Imaging and manipulation of a polar molecule oil Ag(111)

A scanning tunneling microscope (STM) was applied to image and laterally ma nipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolu tion images clearly revealed three characteristic types of appearances (thr ee-lobed, fish and bump shape) for the adsorbed molecules, which could corr espond to three distinct binding configurations. From a detailed analysis o f the relative distance between neighboring three-lobed molecules we determ ine the adsorption site. Applying the lateral manipulation technique ws dem onstrate that the molecule can be pulled, slid or pushed by the tip on the surface. Accompanying with the reposition, molecular rotation and/or changi ng of binding configurations can also be induced. It is found that the dipo le moment of the molecule has minor effects on its lateral movement. The re sults demonstrate that due to many degrees of freedom for large molecules! their manipulating processes can be much more complex in comparison with at oms and small molecules. Such information can shed light on the involved me chanisms on a molecular seals. (C) 2001 Published by Elsevier Science B.V.