Bimodal magnetic force microscopy: Separation of short and long range forces

Li, Jason W.; Cleveland, J. P.; Proksch, Roger

doi:10.1063/1.3126521

Cited by 58 publications

(49 citation statements)

References 16 publications

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“…the fundamental mode and a higher order mode, allows for a simultaneous tracing of both the topography using the interaction response on one mode and compositional information contained in the higher order mode response [9,10]. Transferred to magnetic force microscopy (MFM), a descendant of dSFM, such an approach based on the excitation of two flexural eigenmodes enables a parallel measurement of the sample topography and the long range magnetostatic interactions of the ferromagnetic tip with the sample stray field [11][12][13]. By this means some disadvantages of the widely used twopass MFM technique can be avoided.…”

Section: Multi-frequency Dsfmmentioning

confidence: 99%

Bidirectional quantitative force gradient microscopy

et al. 2015

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Section: Multi-frequency Dsfmmentioning

confidence: 99%

Bidirectional quantitative force gradient microscopy

et al. 2015

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“…However, the use of the intermittent contact mode in vacuum remains challenging. 2 Recently, single passage measurement methods have been reported that use bimodal cantilever excitation suitable for operation in air 5 and in vacuum. 2 They rely on the ability to separate magnetic from non-magnetic (van der Waals or electrostatic) forces on the basis of their different decay lengths.…”

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confidence: 99%

Bimodal magnetic force microscopy with capacitive tip-sample distance control

Schwenk

Zhao

Baćani

et al. 2015

Applied Physics Letters

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A single-passage, bimodal magnetic force microscopy technique optimized for scanning samples with arbitrary topography is discussed. A double phase-locked loop (PLL) system is used to mechanically excite a high quality factor cantilever under vacuum conditions on its first mode and via an oscillatory tip-sample potential on its second mode. The obtained second mode oscillation amplitude is then used as a proxy for the tip-sample distance, and for the control thereof. With appropriate z-feedback parameters two data sets reflecting the magnetic tip-sample interaction and the sample topography are simultaneously obtained.

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“…There the feedback parameter is the amplitude of the cantilever oscillation. Bimodal AFM operation is compatible with the presence of a variety of interaction forces such as mechanical [10,24], electrostatic [21], or magnetic [25]. Kawai et al have demonstrated that bimodal excitation and detection are compatible with frequency modulation AFM operation in an ultrahigh vacuum [26,27].…”

mentioning

confidence: 99%

Noninvasive Protein Structural Flexibility Mapping by Bimodal Dynamic Force Microscopy

Martínez-Martín

Herruzo²,

Dietz³

et al. 2011

Phys. Rev. Lett.

122

121

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Mapping of the protein structural flexibility with sub-2-nm spatial resolution in liquid is achieved by combining bimodal excitation and frequency modulation force microscopy. The excitation of two cantilever eigenmodes in dynamic force microscopy enables the separation between topography and flexibility mapping. We have measured variations of the elastic modulus in a single antibody pentamer from 8 to 18 MPa when the probe is moved from the end of the protein arm to the central protrusion. Bimodal dynamic force microscopy enables us to perform the measurements under very small repulsive loads (30-40 pN). DOI: 10.1103/PhysRevLett.106.198101 PACS numbers: 87.15.Àv, 62.25.Àg, 62.30.+d, 68.37.Ps Ultrahigh resolution, sensitive, and minimally invasive characterization techniques are needed to understand hybrid surfaces integrated by organic, inorganic, and biological structures in air or liquid. Atomic force microscopy (AFM) [1] has enabled molecular resolution images of packed arrays of biomolecules [2-5], sub-2-nm images of individual biomolecules [6], and studying biomolecular interactions in liquid [7]. Single force spectroscopy measurements are already an established tool to measure intermolecular and intrabiomolecule forces [8]; however, those measurements are not compatible with high resolution imaging.Recently, several multifrequency AFM schemes have been proposed to improve high resolution imaging, contrast, and quantitative mapping of material properties [9][10][11][12][13][14][15][16][17][18][19][20][21]. Generically, those schemes exploit the nonlinear character of the tip-surface forces to either activate or detect higher eigenmodes or harmonics and to open new channels to improve imaging and composition sensitivity. Sahin and coworkers [22] have been able to image the protein flexibility of packed two-dimensional bacteriorhodopsin layers by implementing a force time inversion method that exploits the presence of higher harmonics in torsional harmonic cantilevers.In this study, we propose a different dynamic force microscopy approach to image and measure the protein flexibility with molecular resolution. The method combines bimodal excitation with frequency modulation AFM (FM AFM) which allows separating the topography from the protein flexibility mapping. The combined experimental and theoretical findings show that high resolution imaging and protein flexibility mapping can be achieved under the application of extremely low forces ($ 40 pN). Thus, high resolution imaging of isolated proteins in liquid is achieved. The agreement obtained between the nominal height of the protein subunits as determined from diffraction techniques and those reported here implies that the proteins are imaged in liquid in a noninvasive manner.Bimodal dynamic force microscopy involves the mechanical excitation of two cantilever eigenmodes [11,23]; then the cantilever deflection as measured in the photodiode can be expressed as( 1) where z 0 is the mean deflection and Oð"Þ includes other high order terms which are usually...

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Bimodal magnetic force microscopy: Separation of short and long range forces

Cited by 58 publications

References 16 publications

Bidirectional quantitative force gradient microscopy

Bidirectional quantitative force gradient microscopy

Bimodal magnetic force microscopy with capacitive tip-sample distance control

Noninvasive Protein Structural Flexibility Mapping by Bimodal Dynamic Force Microscopy

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