Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes

• Thomas Baumgärtel,
• Christian von Borczyskowski and
• Harald Graaf

Beilstein J. Nanotechnol. 2013, 4, 218–226, doi:10.3762/bjnano.4.22

• application of different software protocols, which were written by using a homemade software user interface. For comparative height measurements, the driving frequency, driving amplitude, setpoint and the AFM tip were kept implicitly constant, as the tip–sample interaction and therefore the measured

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

• interactions (conservative and dissipative) [26] (note that the measured frequency shift is also indirectly affected by dissipation in large-amplitude intermittent-contact experiments, in that dissipative forces can limit penetration of the probe tip into the repulsive region of the tip–sample interaction

• adjusted to the same value (approx. 0.33 nm) during the experiments. To accomplish the same engaged amplitude, three different free amplitudes (that is, amplitudes without tip–sample interaction) had to be used, which were 0.75 nm (AM), 0.58 nm (CE) and 0.33 nm (CA) [35]. In light of this fact it becomes

• the dimensionless time, k is the cantilever force constant (stiffness) and Fts is the tip–sample interaction force. We have also used the approximation A ≈ A0 = F0Q/k [22], where F0 is the amplitude of the inertial excitation force, and have grouped the damping and excitation terms together in

High-resolution dynamic atomic force microscopy in liquids with different feedback architectures

• John Melcher,
• David Martínez-Martín,
• Miriam Jaafar,
• Julio Gómez-Herrero and
• Arvind Raman

Beilstein J. Nanotechnol. 2013, 4, 153–163, doi:10.3762/bjnano.4.15

• -varying deflection x(t) of the probe tip in the presence of tip–sample forces given by where ω0, Q0 and k are the unperturbed natural frequency, quality factor and stiffness of the probe, respectively, and F is the excitation force [19]. Fts is the tip–sample interaction force, which depends explicitly on

• ) = −asinθ. ets is the energy dissipated during the tip–sample interaction and vts is the virial of the tip–sample interaction [25]. The virial is related to the kinetic energy stored in the oscillating probe through the virial theorem [26] and is a measure of the maximum potential energy stored in the tip

• –sample interaction during an oscillation. Moreover, by introducing a specific model for Fts, a relationship between vts and the interaction potential can be established [27]. Finally, both ets and vts have been nondimensionalized by the energy dissipated by the media during an oscillation cycle Emed

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

• tip located on one of the arms of the “T”, the so-called torsional harmonic cantilever (THC), on which the tip–sample interaction generates a torsional oscillation whose amplitude is enhanced by the soft and highly detectable fundamental torsional frequency. Such enhancement provided a more accurate

• on it is the time-dependent tip–sample interaction, fd(t) = Fts[zc(t) + zp(t)], which generates a torsional response that can be linearized in the z-direction, zp(t). Here Fts is the tip–sample interaction force, which is a function of the distance between the tip and the sample (tip position). The

• order to obtain fd(t), that is, the time-dependent tip–sample interaction force acting on the cantilever tip. Finally the force curves are obtained by plotting fd(t) as a function of the vertical tip position, which is generally approximated by the position of the cantilever flexural oscillation, zc(t

Interpreting motion and force for narrow-band intermodulation atomic force microscopy

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

Beilstein J. Nanotechnol. 2013, 4, 45–56, doi:10.3762/bjnano.4.5

• drive signal. In this band, new frequency components spaced by Δω are present, which are generated by the nonlinear tip–sample interaction Fts. Outside the narrow band at ω0 there is only a small response in bands at integer multiples of ω0. The amplitude spectrum of a narrow band signal as a function

Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

• Jannis Lübbe,
• Matthias Temmen,
• Sebastian Rode,
• Philipp Rahe,
• Angelika Kühnle and
• Michael Reichling

Beilstein J. Nanotechnol. 2013, 4, 32–44, doi:10.3762/bjnano.4.4

• cantilever-displacement thermal-noise spectral density as well as the displacement-equivalent noise spectral density introduced by the detection system. This is carried out here in search of the ultimate limits of detection defined by thermal noise, while a systematic study of the tip–sample interaction

• power spectral densities superimposed to the signals. Illustrative representation for the spectral density of the displacement of a cantilever excited to oscillation with 10 nm amplitude at its eigenfrequency f0 = 70 kHz without tip–sample interaction (black curve) and with tip–sample interaction

Calculation of the effect of tip geometry on noncontact atomic force microscopy using a qPlus sensor

• Julian Stirling and
• Gordon A. Shaw

Beilstein J. Nanotechnol. 2013, 4, 10–19, doi:10.3762/bjnano.4.2

• of the tip apex is parallel to the motion of the end of the cantilever (or tine) it can be shown [9] that where Z(L) = azcos(ω0t), and Fts is the force due to the tip–sample interaction. In the case that the motion of the tip is not parallel to the oscillation of the cantilever, more care must be

• taken. Equation 26 can be derived from Newton’s second law in the reference frame of the end of the cantilever where is the force due to the tip–sample interaction as experienced at the end of the cantilever, and meff is the effective mass of the tip and cantilever. Thus, if Equation 26 is modified to

Advanced atomic force microscopy techniques

• Thilo Glatzel,
• Hendrik Hölscher,
• Thomas Schimmel,
• Mehmet Z. Baykara,
• Udo D. Schwarz and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2012, 3, 893–894, doi:10.3762/bjnano.3.99

• , reports on the growing capabilities of AFMs appear. Nearly every physical effect that influences the tip–sample interaction has been used to improve existing modes and to develop new ones. For example, many recently presented techniques include the excitation of higher cantilever oscillation modes; it is

• amazing in how many ways the shaking of a simple cantilever can improve our knowledge about the tip–sample interaction. Another direction is high-speed atomic force microscopy, which is one of the eminent challenges that need to be solved in order to allow the in situ observation of biological processes

Large-scale analysis of high-speed atomic force microscopy data sets using adaptive image processing

• Blake W. Erickson,
• Séverine Coquoz,
• Jonathan D. Adams,
• Daniel J. Burns and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2012, 3, 747–758, doi:10.3762/bjnano.3.84

• distortions cause relative offsets from scan line to scan line. The sources of these distortions include laser-mode hopping and changes in the tip–sample interaction. These 1-D distortions cause apparent discontinuities in the topography of the sample, but do not represent an actual topographic feature. Most

Probing three-dimensional surface force fields with atomic resolution: Measurement strategies, limitations, and artifact reduction

• Mehmet Z. Baykara,
• Omur E. Dagdeviren,
• Todd C. Schwendemann,
• Harry Mönig,
• Eric I. Altman and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2012, 3, 637–650, doi:10.3762/bjnano.3.73

• , empowering experimentalists to characterize the tip–sample interaction in terms of normal forces Fn, potential energies E, and the distance z between the tip apex and the sample surface [4][5][6][7]. More recently, thanks to improvements in the design of atomic force microscopes [8][9] as well as the

• development of new data-acquisition strategies [10][11], DFS measurements have been extended to two and three spatial dimensions. As a result, tip–sample interaction forces and energies can be measured as a function of both the tip–sample distance z and the lateral position (x, y) of the tip apex above the

• ], naphthalocyanine [31], and individual carbon nanotubes [32][33]. Moreover, differentiating the tip–sample interaction energy data in the lateral (x, y) directions has enabled the determination of atomic-scale lateral forces experienced by the probe tip [12]. From such data, the forces required to manipulate single

Mapping mechanical properties of organic thin films by force-modulation microscopy in aqueous media

• Jianming Zhang,
• Zehra Parlak,
• Carleen M. Bowers,
• Terrence Oas and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 464–474, doi:10.3762/bjnano.3.53

• of soft polymeric and biomolecular thin films, requires the inclusion of a viscoelastic model, such as the Voigt model, to explain the tip–sample interaction. Such an approach has recently been shown for contact-resonance imaging in air [32]. However, as before, the cantilever dynamics, which depends

Drive-amplitude-modulation atomic force microscopy: From vacuum to liquids

• Miriam Jaafar,
• David Martínez-Martín,
• Mariano Cuenca,
• John Melcher,
• Arvind Raman and
• Julio Gómez-Herrero

Beilstein J. Nanotechnol. 2012, 3, 336–344, doi:10.3762/bjnano.3.38

• constant by adjusting the amplitude of the driving force. A phase-locked loop (PLL) tracks the effective resonance frequency of the cantilever as it varies as a consequence of the tip–sample interaction. In FM, the position of the scanner in the z-direction is adjusted to keep the frequency shift constant

• oscillation is 20 times higher, so the energy loss due to the tip–sample interaction is usually negligible. As a general rule, in order to enhance the sensitivity, the cantilever oscillation amplitude should be comparable to the selected interaction length [1][2]. Since in AM the energy pumped into the

• cantilever is fixed, the tip gets easily trapped in the sample potential and the image becomes unstable. This effect is particularly relevant in vacuum. In air and liquids the cantilever dissipation originated by the environment is much higher than the dissipation due to tip–sample interaction. Thus, the

Models of the interaction of metal tips with insulating surfaces

• Thomas Trevethan,
• Matthew Watkins and
• Alexander L. Shluger

Beilstein J. Nanotechnol. 2012, 3, 329–335, doi:10.3762/bjnano.3.37

• materials. The origin of the tip–sample interaction close to the surface is due to hybridization of the anion p states with the d states of the tip apex. This interaction mechanism does not give rise to contrast further from the surface (i.e., >4.5 Å); however, the force is still significantly greater above

Combining nanoscale manipulation with macroscale relocation of single quantum dots

• Francesca Paola Quacquarelli,
• Richard A. J. Woolley,
• Martin Humphry,
• Jasbiner Chauhan,
• Philip J. Moriarty and
• Ashley Cadby

Beilstein J. Nanotechnol. 2012, 3, 324–328, doi:10.3762/bjnano.3.36

• performed a contact mode sweep in the area covered by the bitmap. The bitmap defined the areas in which the contact mode setpoint was high, i.e., an increased tip–sample interaction force is present. Figure 2b shows the regions of high contact force and the direction of travel of the AFM probe. Areas for

• which the bitmap was transparent corresponded to regions in which a low tip–sample interaction was required (e.g., close to the QD of interest). The use of manipulation masks of this type enabled a large area of the sample to be swept free of QDs quickly, leaving only the QD of interest (Figure 2c

• around the QD is cleared leaving only two QDs in the centre of the cell. The final QD is removed by nudging the QD with the AFM tip in contact mode with a high tip–sample interaction force. The approximately parallel lines seen in each of the images are atomic step edges on the sapphire substrate. (a) A

Graphite, graphene on SiC, and graphene nanoribbons: Calculated images with a numerical FM-AFM

• Fabien Castanié,
• Laurent Nony,
• Sébastien Gauthier and
• Xavier Bouju

Beilstein J. Nanotechnol. 2012, 3, 301–311, doi:10.3762/bjnano.3.34

• correspond to a qPlus sensor: Aset = 0.2 Å, f0 = 23165 Hz, kc = 1800 N·m−1, Q = 50000. An important input is the tip–sample interaction, which will be described in the following section for the three graphitic structures. Description of the interaction forces In this study, the used model for the tip is

• qualitative agreement with experiments [38][40][42][43] and calculated results [38][44]. Quantitative comparison may be tricky because parameters are different (working parameter set, reactive or inert tip, etc.). In [38], a tip–sample interaction model is based on a Lennard-Jones potential and gives similar

Simultaneous current, force and dissipation measurements on the Si(111) 7×7 surface with an optimized qPlus AFM/STM technique

• Zsolt Majzik,
• Martin Setvín,
• Andreas Bettac,
• Albrecht Feltz,
• Vladimír Cháb and
• Pavel Jelínek

Beilstein J. Nanotechnol. 2012, 3, 249–259, doi:10.3762/bjnano.3.28

• between the tip and the sample. Atomic-scale imaging was achieved later on for both conductors and insulators [3] by means of the so-called static mode. The main drawback of static-mode AFM is the presence of a strong tip–sample interaction, which makes scanning destructive for both the tip and sample

• eV/Hz for “tip B”. The proportional relationship is broken at −76 Hz in the case of “tip A” and −20 Hz in the case of “tip B”. The linear dependence between dissipation and Δf suggests that the origin of the dissipation here is more instrumental (apparent) than related to the tip–sample interaction

Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

• Adam Sweetman,
• Sam Jarvis,
• Rosanna Danza and
• Philip Moriarty

Beilstein J. Nanotechnol. 2012, 3, 25–32, doi:10.3762/bjnano.3.3

• the modelling community that will lead to the investigation of more-realistic tip structures, and their respective tip–sample interaction and contrast mechanisms. The role of the tip was investigated by imaging the well studied Si(100) surface. The Si(100) surface is now understood to form a stable c

• -induced imaging variation At 5 K we routinely observe the c(4 × 2) reconstruction and associated surface defects (Figure 1a). Note that in order to avoid perturbation of the surface during scanning we typically image at a setpoint corresponding to low tip–sample interaction (i.e., at a frequency shift

• principle, available to terminate the apex, each of which may result in a radically different tip–sample interaction [30]. In each image of Figure 1 the apparent positions of the “up” and “down” atoms of the dimers were assigned by checking the registry of the dimer rows against recognised surface features

The atomic force microscope as a mechano–electrochemical pen

• Christian Obermair,
• Andreas Wagner and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2011, 2, 659–664, doi:10.3762/bjnano.2.70

• AFM tip and the sample surface. Instead, a passivated sample surface is activated locally due to lateral forces between the AFM tip and the sample surface. In this way, the area of tip–sample interaction is narrowly limited by the mechanical contact between tip and sample, and well-defined metallic

Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

• Miriam Jaafar,
• Oscar Iglesias-Freire,
• Luis Serrano-Ramón,
• Manuel Ricardo Ibarra,
• Jose Maria de Teresa and
• Agustina Asenjo

Beilstein J. Nanotechnol. 2011, 2, 552–560, doi:10.3762/bjnano.2.59

• taking into account the oxide layer. Regarding the magnetic force, there are widely used models for the magnetic tip–sample interaction, which can be fitted to the experimental data [29], but no simple, well-established function. We can obtain an order of magnitude estimation simply by modeling both the

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle–substrate chemistry and morphology, and of operating conditions

• Samer Darwich,
• Karine Mougin,
• Akshata Rao,
• Enrico Gnecco,
• Shrisudersan Jayaraman and
• Hamidou Haidara

Beilstein J. Nanotechnol. 2011, 2, 85–98, doi:10.3762/bjnano.2.10

• oscillation amplitude of the tip, Aset, was kept constant by a feedback loop. In such cases, the power dissipation accompanying the tip-sample interaction can be determined from the following relationship [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]: where Apiezo is the oscillation

• constants of 5 and 48 N/m (respectively, MPP12100 from Veeco and PPP-NCLR from Nanosensors) were used. During manipulation, the oscillation amplitude of the tip, Aset, was kept constant by a feedback loop. In this case, the power dissipation accompanying the tip–sample interaction can be determined from

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

• Thomas König,
• Georg H. Simon,
• Lars Heinke,
• Leonid Lichtenstein and
• Markus Heyde

Beilstein J. Nanotechnol. 2011, 2, 1–14, doi:10.3762/bjnano.2.1

• measurements and the corresponding theoretical results are presented in Figure 8. At the defect site, the tip-sample interaction increases significantly with decreasing distance. From a structural point of view the positions of the defects are ”holes”, i.e., missing oxygen atoms in the lattice. In the first

Tip-sample interactions on graphite studied using the wavelet transform

• Giovanna Malegori and
• Gabriele Ferrini

Beilstein J. Nanotechnol. 2010, 1, 172–181, doi:10.3762/bjnano.1.21

• , i.e., signal with a frequency spectrum changing during the data collection. This work will show that the tip-sample interaction forces can be quantitatively measured using CWT with acquisition times as short as few tens of milliseconds, as required for practical DFS imaging. Since wavelets are a

• of the PSD as a function of z. Considering each flexural mode equivalent to a mass-spring system, the tip-sample interaction elastic constant kts = −dFts/dz is expressed as a function of the resonant frequency as , where is the resonant frequency of the free cantilever, is the resonant frequency of

• effect of the tip-sample interaction dominates. Continuous wavelet transform and time-frequency resolution The FT analysis provides a frequency representation of a signal with perfect spectral resolution but without the possibility to correlate the frequency spectrum with the signal evolution in time

Sensing surface PEGylation with microcantilevers

• Natalija Backmann,
• Natascha Kappeler,
• Thomas Braun,
• François Huber,
• Hans-Peter Lang,
• Christoph Gerber and
• Roderick Y. H. Lim

Beilstein J. Nanotechnol. 2010, 1, 3–13, doi:10.3762/bjnano.1.2

• on the AFM images can be understood by comparing the tip-sample interaction forces obtained in PBS and 20% 2-propanol, respectively (Figure 5). Specifically, the thickness of the PEG layer (defined by the onset of repulsion) reduces from 26 nm in the brush-like state to 5 nm in the collapsed state