Systematically Navigating Through the Parameter Space During the Lateral Manipulation of PTCDA on the Ag(111) Surface.

Abstract

The lateral manipulation of single perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules serves as a key model process for both building surface-supported nanostructures and enabling quantum sensing with single molecules attached to scanning probe microscopy tips. This work introduces an instructive procedure that guarantees the controlled lateral movement of single PTCDA molecules, in particular the isolation from molecular island edges. The lateral manipulation relies on establishing a specific bond between one of the molecular carboxylic oxygen atoms and the metallic tip of a combined scanning tunneling (STM) and atomic force microscope (AFM) before displacing the molecule by laterally moving the tip. From analyzing both the tip-position data during this movement and the STM imaging contrast after the manipulation, a categorization scheme containing four resulting tip-molecule-surface configurations is proposed. Together with transitions observed between some of these configurations, the complex tip-molecule-surface system parameter space during the manipulation procedure can be compressed into an instructive flowchart. Following through this flowchart guarantees the lateral isolation of a single PTCDA molecule in a systematic manner and without requirement for previous knowledge. Broad applicability is verified by also manipulating molecules from Ag(111) surface step-edges and from molecular island edges on the Au(111) surface.