Mapping of conservative and dissipative interactions in bimodal atomic force microscopy using open-loop and phase-locked-loop control of the higher eigenmode

Chawla, Gaurav; Solares, Santiago D.

doi:10.1063/1.3626847

Cited by 62 publications

(74 citation statements)

References 26 publications

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“…[11][12][13] It was shown that the small oscillation of the second flexural mode could be used to increase sensitivity to material properties. [14][15][16][17] Several groups have applied this technique to biological samples, including antibodies 13 and proteins. 11 Schwenk and coworkers used bimodal AFM to increase the contrast stemming from magnetic interaction with a ferromagnetic tip.…”

mentioning

confidence: 99%

Amplitude dependence of image quality in atomically-resolved bimodal atomic force microscopy

Ooe

Kirpal

Wastl

et al. 2016

Applied Physics Letters

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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.

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confidence: 99%

Amplitude dependence of image quality in atomically-resolved bimodal atomic force microscopy

Ooe

Kirpal

Wastl

et al. 2016

Applied Physics Letters

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“…In such cases, as long as the oscillation is not chaotic, the user will generally be able to obtain an image, but imaging stability does not guarantee that the results are physically meaningful, since it does not guarantee that the contrast eigenmodes conform to the assumed ideal response. In contrast, if frequency modulation methods are used to drive the higher modes [5,7,27], it is necessary that the frequency response be well behaved both to ensure the stability of the controls scheme and to guarantee physically meaningful results. Our simulations show that the highest (least perturbable) eigenmodes retain their ideal response even in multimodal operation.…”

Section: Resultsmentioning

confidence: 99%

Multi-frequency tapping-mode atomic force microscopy beyond three eigenmodes in ambient air

Solares¹,

An²,

Long³

2014

Beilstein J. Nanotechnol.

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SummaryWe present an exploratory study of multimodal tapping-mode atomic force microscopy driving more than three cantilever eigenmodes. We present tetramodal (4-eigenmode) imaging experiments conducted on a thin polytetrafluoroethylene (PTFE) film and computational simulations of pentamodal (5-eigenmode) cantilever dynamics and spectroscopy, focusing on the case of large amplitude ratios between the fundamental eigenmode and the higher eigenmodes. We discuss the dynamic complexities of the tip response in time and frequency space, as well as the average amplitude and phase response. We also illustrate typical images and spectroscopy curves and provide a very brief description of the observed contrast. Overall, our findings are promising in that they help to open the door to increasing sophistication and greater versatility in multi-frequency AFM through the incorporation of a larger number of driven eigenmodes, and in highlighting specific future research opportunities.

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“…However, the difficulties become even more significant if one wishes to implement bimodal operations involving frequency modulation (FM) control of the higher eigenmode [4]. While the phase contrast results may become less and less meaningful as momentary perturbations become more and more severe, one is still generally able to obtain an image with open loop drive of the higher mode.…”

Section: Resultsmentioning

confidence: 99%

Challenges and complexities of multifrequency atomic force microscopy in liquid environments

Solares¹

2014

Beilstein J. Nanotechnol.

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SummaryThis paper illustrates through numerical simulation the complexities encountered in high-damping AFM imaging, as in liquid enviroments, within the specific context of multifrequency atomic force microscopy (AFM). The focus is primarily on (i) the amplitude and phase relaxation of driven higher eigenmodes between successive tip–sample impacts, (ii) the momentary excitation of non-driven higher eigenmodes and (iii) base excitation artifacts. The results and discussion are mostly applicable to the cases where higher eigenmodes are driven in open loop and frequency modulation within bimodal schemes, but some concepts are also applicable to other types of multifrequency operations and to single-eigenmode amplitude and frequency modulation methods.

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Mapping of conservative and dissipative interactions in bimodal atomic force microscopy using open-loop and phase-locked-loop control of the higher eigenmode

Cited by 62 publications

References 26 publications

Amplitude dependence of image quality in atomically-resolved bimodal atomic force microscopy

Amplitude dependence of image quality in atomically-resolved bimodal atomic force microscopy

Multi-frequency tapping-mode atomic force microscopy beyond three eigenmodes in ambient air

Challenges and complexities of multifrequency atomic force microscopy in liquid environments

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