| In ambient conditions true non-contact Dynamic Scanning Force Microscopy (NC-DSFM) is performed with tip-sample distances of the order of several nanometers, correspondingly dissipation mechanisms such as typically observed in UHV conditions can be excluded. Also, dissipation mechanisms as observed in intermittent contact mode ("tapping mode") can be excluded, since no tip-sample contact is established. Nevertheless, dissipation is experimentally observed. In the present work we study the noise measured in the tip-sample system in order to explore the dissipation mechanism that may be relevant for NC-DSFM in ambient conditions. Using lock-in techniques, we measure the noise of the tip-sample interaction during spectroscopy experiments, as well as during image acquisition. We show that noise is much larger than that expected due to thermal fluctuation and relate this additional noise to dissipation in the tip-sample system (fluctuation-dissipation theorem). We believe our results are important not only important to establish the detection limits of DSFM, but also to explore the fundamental mechanism for dissipations in DSFM experiments performed in ambient conditions. |
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