Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 14: New Methods and Developments 2: Scanning Probe Techniques 2 (joint session O/KFM)
O 14.2: Vortrag
Montag, 5. September 2022, 15:15–15:30, S053
Chemical bond imaging using torsional and flexural higher eigenmodes of qPlus sensors — •Daniel Martin-Jimenez1, Michael G. Ruppert2, Alexander Ihle1, Sebastian Ahles3, Hermann A. Wegner3, André Schirmeisen1, and Daniel Ebeling1 — 1Institute of Applied Physics, Justus Liebig University Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany). — 2University of Newcastle, Callaghan, NSW, 2308 (Australia). — 3Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen (Germany).
Non-contact atomic force microscopy (AFM) with CO-functionalized tips allows to visualize the chemical structure of adsorbed molecules and identify individual inter- and intramolecular bonds. Herein, we analyze the suitability of qPlus sensors, which are commonly used for bond imaging, for the application of modern multifrequency AFM techniques. Two different qPlus sensors were tested for submolecular resolution imaging via actuating torsional and flexural higher eigenmodes and via bimodal AFM. The torsional eigenmode of the first sensor is perfectly suited for performing lateral force microscopy (LFM) with single bond resolution. The advantage of using a torsional eigenmode is that the same molecule can be imaged either with a vertically or laterally oscillating tip without replacing the sensor simply by actuating a different eigenmode. Submolecular resolution is also achieved by actuating the 2nd flexural eigenmode of our second sensor. With laser Doppler vibrometry measurements and AFM simulations we can rationalize the image contrast mechanism of the 2nd eigenmode.