2016/05/21 by Hiroaki Ooe, Dominik Kirpal, Daniel S. Wastl +3 · 2 citations
Engineering · Physics and Astronomy · #Force Microscopy Techniques and Applications #Mechanical and Optical Resonators #Near-Field Optical Microscopy #cond-mat.mes-hall
paper · pdf · doi:10.1063/1.4964125
3000 words, 3 Figures, 3 supplimentary figures
arxiv created 2016/05/21 · openalex created_date 2016/06/24 · openalex publication_date 2016/10/03 · arxiv updated 2016/11/03 · openalex updated_date 2026/07/28
In bimodal FM-AFM, two flexural modes are excited simultaneously. The total vertical oscillation deflection range of the tip is the sum of the peak-to-peak amplitudes of both flexural modes (sum amplitude). We show atomically resolved images of KBr(100) in ambient conditions in bimodal AFM that display a strong correlation between image quality and sum amplitude. When the sum amplitude becomes larger than about 200 pm, the signal-to-noise ratio (SNR) is drastically decreased. We propose this is caused by the temporary presence of one or more water layers in the tip-sample gap. These water layers screen the short range interaction and must be displaced with each oscillation cycle. Further decreasing the sum amplitude, however, causes a decrease in SNR. Therefore, the highest SNR in ambient conditions is achieved when the sum amplitude is slightly less than the thickness of the primary hydration layer.