Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

• Babak Eslami,
• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1144–1151, doi:10.3762/bjnano.5.125

• imaging modes is now available, each with its own capabilities and applications. Among them, a family of techniques known as multifrequency AFM [2][3][4][5][6][7][8][9][10][11] has expanded considerably since the introduction of the first bimodal method by Rodriguez and Garcia in 2004 [12]. In

• multifrequency AFM the cantilever probe is driven simultaneously at more than one frequency, with the objective of creating additional channels of information in order to provide a more complete picture of the sample morphology and properties [2]. In the original method of Garcia and coworkers [12][13] the first

Challenges and complexities of multifrequency atomic force microscopy in liquid environments

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 298–307, doi:10.3762/bjnano.5.33

• operations and that the various issues compound with the added complexity of multifrequency AFM [9][29][30][31][32], such that more and more experience and knowledge is required from the user to carry out meaningful measurements. With multifrequency methods it can be more difficult to achieve suitable

• environments for which the eigenmode bandwidth is greater [21][26]. This phenomenon also occurs in multifrequency AFM with the added complexity that the tip–sample forces depend strongly on the parameters chosen to drive the higher eigenmodes, as well as on their nonlinear interaction with the fundamental

• differences between base- and tip-excited systems have also been previously discussed for single-mode operation [19][24][28], but as for the issues discussed in the two previous sections, they are worth revisiting here in the specific context of multifrequency AFM. These differences are not extremely relevant

Frequency, amplitude, and phase measurements in contact resonance atomic force microscopies

• Gheorghe Stan and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 278–288, doi:10.3762/bjnano.5.30

• ), respectively [15][16][17][18][19][20]. In the last ten years, intermittent-contact measurements have been enhanced through multifrequency excitation methods [21][22][23][24][25][26][27]. In multifrequency AFM, the fundamental cantilever eigenmode is typically controlled in conventional AM- or FM-AFM mode for

Unlocking higher harmonics in atomic force microscopy with gentle interactions

• Sergio Santos,
• Victor Barcons,
• Josep Font and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2014, 5, 268–277, doi:10.3762/bjnano.5.29

• mapping of compositional variations [25] or as a closed loop, in which case the tip–sample stiffness kts can be computed [17][26]. More recently, the multifrequency AFM approach has been extended to employ three flexural modes [27] and/or simultaneous torsional modes [28], for which, typically, the

Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

• Daniel Kiracofe,
• Arvind Raman and
• Dalia Yablon

Beilstein J. Nanotechnol. 2013, 4, 385–393, doi:10.3762/bjnano.4.45

• methods to calibrate stiffness and optical lever sensitivity of higher order eigenmodes. The current state of the art works well for the first few eigenmodes but becomes less reliable for third and higher modes. As multifrequency AFM evolves toward quantitative measurements using higher order eigenmodes

Polynomial force approximations and multifrequency atomic force microscopy

• Daniel Platz,
• Daniel Forchheimer,
• Erik A. Tholén and
• David B. Haviland

Beilstein J. Nanotechnol. 2013, 4, 352–360, doi:10.3762/bjnano.4.41

• measurements [5][6][7][8][9][10] is a strong driving force for the development of atomic force microscopy (AFM). The advent of multifrequency AFM resulted in a variety of new measurement techniques enabling enhanced contrast and spatial mapping of surface properties on a wide range of samples [11]. However

• , multifrequency AFM creates more data than conventional AFM, which both complicates the interpretation of measurement results and offers the possibility of much more detailed surface analysis. One of the goals when interpreting AFM data is the reconstruction of the force between a surface and the sharp tip at the

• (yellow line) and an ADFS reconstruction (red circles). Over the full range of oscillation both curves agree well. Good agreement is also observed at all other z-piezo extensions. Conclusion Multifrequency AFM opens the window to a wide variety of novel AFM measurement techniques enabling a much improved

Bimodal atomic force microscopy driving the higher eigenmode in frequency-modulation mode: Implementation, advantages, disadvantages and comparison to the open-loop case

• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2013, 4, 198–207, doi:10.3762/bjnano.4.20

• of the second phase contrast to material properties in the small-amplitude regime. This method, which was later implemented experimentally [3] and studied further theoretically and computationally [4][5], gave birth to a new host of multifrequency AFM techniques, which nowadays include a wide variety

• ), f1 = 92.4 kHz, k1 = 2.0 N/m, Q1 = 208, f2 = 586.8 kHz, k2 = 97.6 N/m, Q2 = 678). 500 × 800 nm2 sized images of DNA/mica samples in three different multifrequency AFM modes (AM-OL, AM-FM (CE), AM-FM (CA)). Data channels in rows from top to bottom show: height, 1st amplitude, 1st phase shift, 2nd

Towards 4-dimensional atomic force spectroscopy using the spectral inversion method

• Jeffrey C. Williams and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2013, 4, 87–93, doi:10.3762/bjnano.4.10

• phenomena take place when imaging samples in high-damping (liquid) environments [18] or in multifrequency AFM characterization [19]. Illustration of the surface depression by the tip–sample impact, and successive recovery within the standard linear solid model. Z1 is the undisturbed surface position, before