SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 91: Poster Session VII: Scanning probe techniques: Method development II
O 91.2: Poster
Donnerstag, 4. März 2021, 10:30–12:30, P
Theoretical models for KPFM with flexible tip apexes — •Ondrej Krejci1 and Adam S. Foster1,2,3 — 1Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland — 2Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128, Germany — 3WPI-NanoLSI, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
Kelvin Probe Force Microscopy (KPFM) started as a technique with the possibility to determine areas of a sample with different work functions [1], but as lateral resolution moved towards (sub)angstrom precision, it found its place also in identifying differently charged parts of molecules (e.g. [2]). This ability was in specific cases used in KPFM to obtain chemical resolution using SPM [3,4,5]. On the other hand, the exact interpretation of KPFM data with flexible tip apices (e.g. CO-tip) remains unknown. In this work, we will summarise up-to-date knowledge about KPFM [1,4,6] focusing mainly on measurements with FM-AFM/STM. Based upon this, we will present a new model for electrostatic field, which is describing the experiments with CO-metal tips [5] and metal substrates. This new electrostatic model is applied in a DFT calculations simulating the full tip-sample system. These calculations will be compared with simple mechanistic models capturing various sources of achieved signal. With this, we aim to recover the physics behind KPFM with flexible tip apices.
Ref: [1] APL 58, 2921 (1991). [2] Nat. Nanotechnol. 7, 227-231 (2012). [3] Nano Lett. 14, 3342-3346 (2014) [4] PRB, 90, 155455 (2014). [5] ACS Nano 12, 5274-5283 (2018) [6] PRB 86, 075407 (2012).