Selective resolution of phonon modes in STM-IETS on clean and oxygen-adsorbed Cu(100) surfaces

TL;DR

This study demonstrates selective measurement of surface phonon modes on Cu(100) surfaces using STM-IETS, revealing how tip and surface structures influence phonon detection and providing insights into surface stress relaxation.

Contribution

It introduces a method for selective phonon mode resolution in STM-IETS and explains the observed modes through selection rules, advancing surface phonon analysis techniques.

Findings

Different phonon modes observed depending on tip and surface structure.

Surface stress relaxation detected via spatial variation in STM-IETS.

Surface phonon energies identified at 19.0 meV and 13.5 meV for clean and oxygen-adsorbed surfaces.

Abstract

The observation of surface phonon dispersion using local probes can provide important information related to local structural and thermal properties. In this study, surface phonon modes on a Cu(100) surface were measured using the inelastic tunneling spectroscopy of scanning tunneling microscopy (STM-IETS) with atomically sharp tips. Different phonon modes were selectively measured depending on the structures of the probing tips or the surfaces. Two different surface phonon modes, at 19.0 meV on a clean Cu(100) surface and at 13.5 meV on an oxygen-adsorbed Cu(100) surface, are explained by the selection rules. Additionally, the spatial variation in STM-IETS showed surface stress relaxation.