Quantification of van der Waals forces in bimodal and trimodal AFM

Sergio Santos; Karim Gadelrab; Lamiaa Elsherbiny; Xaver Drexler; Tuza Olukan; Josep Font; Victor Barcons; Matteo Chiesa

doi:10.1063/5.0154196

Quantification of van der Waals forces in bimodal and trimodal AFM

J Chem Phys. 2023 May 28;158(20):204703. doi: 10.1063/5.0154196.

Authors

Sergio Santos¹, Karim Gadelrab², Lamiaa Elsherbiny³, Xaver Drexler¹, Tuza Olukan¹, Josep Font⁴, Victor Barcons⁴, Matteo Chiesa^{1

3}

Affiliations

¹ UiT-the Arctic University of Norway, Department of Physics and Technology, 9037 Tromsø, Norway.
² Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
³ Laboratory for Energy and NanoScience (LENS), Khalifa University of Science and Technology, Masdar Institute Campus, 127788 Abu Dhabi, United Arab Emirates.
⁴ Departament d'Enginyeria Minera, Industrial i TIC, UPC BarcelonaTech, 08242 Manresa, Spain.

PMID: 37212408
DOI: 10.1063/5.0154196

Abstract

The multifrequency formalism is generalized and exploited to quantify attractive forces, i.e., van der Waals interactions, with small amplitudes or gentle forces in bimodal and trimodal atomic force microscopy (AFM). The multifrequency force spectroscopy formalism with higher modes, including trimodal AFM, can outperform bimodal AFM for material property quantification. Bimodal AFM with the second mode is valid when the drive amplitude of the first mode is approximately an order of magnitude larger than that of the second mode. The error increases in the second mode but decreases in the third mode with a decreasing drive amplitude ratio. Externally driving with higher modes provides a means to extract information from higher force derivatives while enhancing the range of parameter space where the multifrequency formalism holds. Thus, the present approach is compatible with robustly quantifying weak long range forces while extending the number of channels available for high resolution.