Single-Molecule Characterization of Van Der Waals Contact Between Alkane and Gold

Van der Waals (vdW) contact, dominated by weak but ubiquitous vdW interactions, plays a significant role in diverse fields such as supramolecular chemistry, nanotechnology, and surface science. Accurate characterization of vdW contact at the single-molecule level remains challenging. Herein, we combine the scanning tunneling microscope break junction technique with first-principles calculations to study the mechanical and electrical characteristics of the alkane/Au vdW contact in an in -situ solution environment. The step -like conductance plateaus indicate a gradual desorption of alkyl chains in units of two methylene groups under force stretching. Two distinct charge transport channels, through the shortest C-H/Au pathway and the entire adsorbed alkyl chain, are identified. Furthermore, we discover that a higher electric field leads to increased conductance and stronger bonding of the alkane/Au vdW contact. These results unveil the intrinsic properties of vdW contact at the molecular and even atomic levels, which are crucial for exploring noncovalent interactions and advancing molecular sciences.