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

No Thumbnail Available
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2018-06-26
Major/Subject
Mcode
Degree programme
Language
en
Pages
10
5274-5283
Series
ACS Nano, Volume 12, issue 6
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.
Description
Keywords
elemental contrast, hexagonal boron nitride, Kelvin probe force microscopy (KPFM), noncontact atomic force microscopy (nc-AFM), van der Waals density functional theory
Other note
Citation
Schulz , F , Ritala , J , Krejčí , O , Seitsonen , A P , Foster , A S & Liljeroth , P 2018 , ' Elemental Identification by Combining Atomic Force Microscopy and Kelvin Probe Force Microscopy ' , ACS Nano , vol. 12 , no. 6 , pp. 5274-5283 . https://doi.org/10.1021/acsnano.7b08997