Scanning tunneling microscopy using CO-terminated probes with tilted and straight geometries

TL;DR

This study combines experimental STM imaging with simulations to analyze how the tilt angle of CO-terminated tips affects the imaging of Cu atoms and molecules, revealing the role of tip orbitals.

Contribution

It introduces a detailed analysis of CO tip tilt effects on STM topographies using combined experimental and simulation approaches.

Findings

Tip tilt angle significantly influences STM images.

Simulations accurately reproduce experimental topographies.

Tip orbital composition affects tunneling current characteristics.

Abstract

Scanning tunneling microscopy using a CO-functionalized tip is combined with simulations to explore the impact of the CO tilt angle on topographies of a single Cu atom and CO molecule adsorbed on Cu(111). Images of the Cu atom acquired with varying tip tilt angles and sample voltages are reproduced by the calculations. The agreement between measured and simulated data allows to unveil the tip-orbital composition of the tunneling current, which highlights the role of the different p-orbitals of the CO tip. Microscope data of adsorbed CO and their dependence on voltage and probe-surface distance are captured for the nontilted junction geometry and in the limit of weak tip-surface interaction assuming sufficiently large tip-sample separations.