# Magnification effects in scanning tunneling microscopy: the role of surface radicals

## TL;DR

This paper reveals how polarized surface radicals can cause magnification effects in STM images, leading to potential misinterpretation of atomic structures on surfaces with directional bonds, especially in silicon and germanium.

## Contribution

It provides a physical explanation for magnification effects in STM caused by surface radicals, highlighting an overlooked factor in surface structure analysis.

## Key findings

- Polarized surface radicals cause magnification effects in STM images.
- Spurious images can suggest false atomic positions.
- Magnification observed on silicon and germanium surfaces.

## Abstract

Scanning tunneling microscopy (STM) is a fundamental tool for determination of the surface atomic structure. However, the interpretation of high resolution microscopy images is not straightforward. In this paper we provide a physical insight on how STM images can suggest atomic locations which are distinctively different from the real ones. This effect should be taken into account when interpreting high-resolution STM images obtained on surfaces with directional bonds. It is shown that spurious images are formed in the presence of polarized surface radicals showing a pronounced angle with respect to the surface normal. This issue has been overlooked within the surface science community and often disregarded by experimentalists working with STM. Without loss of generality, we illustrate this effect by the magnification observed for pentamer-like structures on (110), (113) and (331) surfaces of silicon and germanium.