Recently we received a commentary by Passian et al. [1] on our previously published paper [2] in the Ultramicroscopy. Although the commentators, who are also our co-authors in an earlier papers in similar line (see [3,5]), claimed to discuss and better explain the concept of "virtual resonance" in [3], they went on to conclude that the experimental results and findings in [3] have been misrepresented in [2]. We have theoretically considered a general semi-empirical nonlinear interaction force consisting of different terms with which the dynamic response of the system could be very dependent. Here, we highlight these types of dependencies on the amplitude at the difference frequency. Due to the nature of this communication, we would like to limit our response to matters of fact to the authors of the commentary.
Keywords: AFM microcantilevers; Subsurface imaging; Tip–sample interaction forces.
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