Smoluchowski Effect at a Sub-Å Step on Pb/Cu (111) Revealed by Field Emission Resonance Spectroscopy

Poonam Borhade^1*, Shin-Ming Lu¹, Wen-Yuan Chan², Ho-Hsiang Chang¹, Wei-Bin Su¹

¹Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan
²Department of Electronic Engineering, Mingshin University of Science and Technology, Hsinchu, Taiwan

* Presenter:Poonam Borhade, email:borhadepoonam2310@gmail.com

A sub Å-high surface step can form on Pb films grown on a Cu (111) substrate due to the mismatch between the interlayer spacing of Pb (111) and the single-step height on Cu (111), which is significantly smaller than the typical 2–3 Å step height on most materials. The Smoluchowski effect, a charge-transfer phenomenon that induces the electric dipole at surface steps, has previously been observed for single atomic steps. In this work, we demonstrate that this effect can persist even at a step as small as 0.5 Å, as revealed by field emission resonance spectroscopy combined with a triangular potential model. Because the work function of Pb films oscillates with the number of atomic layers, the effect is verified for the case where the higher terrace possesses a higher work function, thereby excluding the possibility that the observed dipole arises from a work function difference.

Keywords: Smoluchowski effect, field emission resonance spectroscopy, sub Å-high step