Quantum Coherence of Image-Potential States

TL;DR

This paper investigates the quantum coherence of image-potential states on Cu(100) surfaces using STM/STS, revealing their dispersion, phase-relaxation times, and the impact of tip-induced Stark shifts.

Contribution

It provides the first measurement of the dispersion relation and phase-relaxation times of image-potential states via quantum interference patterns.

Findings

Determined the dispersion relation of the first image-potential state.

Measured the momentum-resolved phase-relaxation time.

Showed tip-induced Stark shift does not affect electron motion parallel to the surface.

Abstract

The quantum dynamics of the two-dimensional image-potential states in front of the Cu(100) surface is measured by scanning tunneling microscopy (STM) and spectroscopy (STS). The dispersion relation and the momentum resolved phase-relaxation time of the first image-potential state are determined from the quantum interference patterns in the local density of states (LDOS) at step edges. It is demonstrated that the tip-induced Stark shift does not affect the motion of the electrons parallel to the surface.