First principles theory of inelastic currents in a scanning tunneling microscope

TL;DR

This paper develops a first principles theoretical framework for inelastic tunneling in scanning tunneling microscopy, linking vibrational effects to measurable tunneling currents and desorption rates, validated by experimental comparison.

Contribution

It extends elastic tunneling theory to include inelastic effects, providing a quantitative method to analyze vibrational heating and desorption in STM.

Findings

Inelastic current relates to changes in local density of states due to adsorbates.

Calculated desorption rates match experimental data.

Theory predicts bias and current dependence of vibrational heating.

Abstract

A first principles theory of inelastic tunneling between a model probe tip and an atom adsorbed on a surface is presented, extending the elastic tunneling theory of Tersoff and Hamann. The inelastic current is proportional to the change in the local density of states at the center of the tip due to the addition of the adsorbate. We use the theory to investigate the vibrational heating of an adsorbate below an STM tip. We calculate the desorption rate of H from Si(100)-H(2$\times$1) as function of the sample bias and tunnel current, and find excellent agreement with recent experimental data.