Elemental Identification by Combining Atomic Force Microscopy and Kelvin Probe Force Microscopy

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • Ecole Normale Superieure
  • Kanazawa University
  • Graduate School Materials Science in Mainz

Abstract

There are currently no experimental techniques that combine atomic-resolution imaging with elemental sensitivity and chemical fingerprinting on single molecules. The advent of using molecular-modified tips in noncontact atomic force microscopy (nc-AFM) has made it possible to image (planar) molecules with atomic resolution. However, the mechanisms responsible for elemental contrast with passivated tips are not fully understood. Here, we investigate elemental contrast by carrying out both nc-AFM and Kelvin probe force microscopy (KPFM) experiments on epitaxial monolayer hexagonal boron nitride (hBN) on Ir(111). The hBN overlayer is inert, and the in-plane bonds connecting nearest-neighbor boron and nitrogen atoms possess strong covalent character and a bond length of only ∼1.45 Å. Nevertheless, constant-height maps of both the frequency shift Δf and the local contact potential difference exhibit striking sublattice asymmetry. We match the different atomic sites with the observed contrast by comparison with nc-AFM image simulations based on the density functional theory optimized hBN/Ir(111) geometry, which yields detailed information on the origin of the atomic-scale contrast.

Details

Original languageEnglish
Pages (from-to)5274-5283
Number of pages10
JournalACS Nano
Volume12
Issue number6
Publication statusPublished - 26 Jun 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • elemental contrast, hexagonal boron nitride, Kelvin probe force microscopy (KPFM), noncontact atomic force microscopy (nc-AFM), van der Waals density functional theory

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