Surface State Stark Shift in a Scanning Tunneling Microscope

TL;DR

This study investigates how electric fields in a scanning tunneling microscope affect the surface state energy of Ag(111), revealing a Stark shift that can be quantitatively modeled and aligns with photoemission data.

Contribution

It provides a detailed quantitative analysis of the Stark effect on surface states in STS over a wide current range, supported by a theoretical model.

Findings

Stark effect causes a measurable shift in surface state energy.

The energy shift can be accurately modeled with a 1D potential.

Results agree with recent photoemission spectroscopy measurements.

Abstract

We report a quantitative low-temperature Scanning Tunneling Spectroscopy (STS)study on the Ag(111) surface state over an unprecedented range of currents (50 pA to 6 $\mu$A)through which we can tune the electric field in the tunnel junction of the microscope. We show that in STS a sizeable Stark effect causes a shift of the surface state binding energy $E_{0}$.Data taken are reproduced by a one-dimensional potential model calculation, and are found to yield a Stark-free energy $E_{0}$ in agreement with recent state-of-the-art Photoemission Spectroscopy measurements.