Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 16: Scanning Probe Techniques: Method Development
O 16.1: Talk
Monday, March 17, 2025, 15:00–15:15, H25
Fast and quantitative nanomechanical mapping using photothermal off-resonance tapping atomic force microscopy (AFM) — •Gunstheimer Hans1,2, Fläschner Gotthold1, Adams Jonathan1, Hölscher Hendrik2, and Hoogenboom Bart1 — 1Nanosurf AG, Gräubernstrasse 12-14, 4410 Liestal, Switzerland — 2Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology, Karlsruhe, Germany
Multifunctional imaging, makes AFM a powerful tool for nanoscale surface analysis. However, most scanner-based methods for measuring mechanical properties are slow, limiting their use in fast mapping of mechanical characteristics. The main source of limitation is the piezo scanner, used to modulate tip-sample distance. This can be overcome by direct cantilever actuation, such as photothermal excitation. By moving the cantilever's comparably smaller mass, higher actuation bandwidths are accessible, enabling new approaches for AFM-based nanomechanical characterization. Here, we share insights on applying photothermal off-resonance tapping to fast nanomechanical property mapping. Based on simulations of cantilever bending due to laser-induced heating, we predict the cantilever response and propose a procedure to convert thermomechanical cantilever behavior into a calibrated nanomechanical measurement. We present the experimental method validation by measurements of polymer samples and reference structures. This novel photothermal off-resonance tapping mode enables quantitative nanomechanical mapping at frequencies of several tens of kHz, unlocking new insights into dynamic sample behavior.
Keywords: nanomechanics; atomic force microscopy; AFM; force spectroscopy; photothermal excitation