AVS 66th International Symposium & Exhibition
    Nanometer-scale Science and Technology Division Thursday Sessions
       Session NS+2D+QS-ThM

Paper NS+2D+QS-ThM6
Using Controlled Manipulation of Molecules to Trace Potential Energy Surfaces of Adsorbed Molecules

Thursday, October 24, 2019, 9:40 am, Room A222

Session: Direct Atomic Fabrication by Electron and Particle Beams & Flash Session
Presenter: Eric Altman, Yale University
Authors: O.E. Dagdeviren, Yale University
C. Zhou, Yale University
M. Todorovic, Aalto University, Finland
E.I. Altman, Yale University
U.D. Schwarz, Yale University
Correspondent: Click to Email
The development of scanning probe microscopy techniques has enabled the manipulation of single molecules. More recently it has been demonstrated that the forces and energy barriers encountered along the manipulation path can be quantified using non-contact atomic force microscopy (AFM). To explore the practicality of using this novel approach to experimentally measure the energy barriers an adsorbed molecule encounters as it moves across a surface decorated by other molecules including potential reaction partners, we have been studying benzene molecules on Cu (100) as a model system. We first choose a specific manipulation path and then move the tip repeatedly along this path as the tip-sample distance is reduced while recording the AFM cantilever oscillation amplitude and phase. To preserve the accurancy of the recovered tip-sample interaction potentials and forces, we use oscillation amplitudes significantly larger than the decay length of the tip-sample interaction potential are used. Operating the microscopy in the tuned-oscillator mode and analyzing the resulting cantilever oscillation amplitude and phase as functions of the spatial coordinates allows recovery of the potential energy of the interaction between the tip and the sample, the force on the tip normal to the surface, and the lateral force acting on the tip along the manipulation path, all as functions of tip vertical and lateral position with 0.01 Å resolution. In over 50 distinct maniupluation events, the molecules were either pushed, pulled, jumped to the tip, or did not move depending on the chemical environment surrounding the molecule and the chemical identity of the tip. For further insight, we have compared the experimentally measured energy landscapes and manipulation outcomes with computational results obtained using a Bayesian Optimization Structure Search protocol.