High-frequency multimodal atomic force microscopy

• Adrian P. Nievergelt,
• Jonathan D. Adams,
• Pascal D. Odermatt and
• Georg E. Fantner

Beilstein J. Nanotechnol. 2014, 5, 2459–2467, doi:10.3762/bjnano.5.255

• of the cantilever (P0) as where V0 is the excitation voltage, f0 the excitation frequency, k the spring constant, A the amplitude and Q the quality factor far from the surface [39]. The acquired dissipation is, to a first approximation, only dependent on the materials properties and the additional

• and inversely with the quality factor. The increased ratio of resonance frequency to spring constant makes it clear that the use of small cantilevers is ideally suited for low-dissipation imaging on multiple dynamic modes. Drive amplitude modulation imaging For biophysical imaging with atomic force

• in water [40]. One issue of note is that higher eigenmodes have an inherently higher dynamic stiffness that can be up to two orders of magnitude larger than the fundamental mode. This can be problematic for softer samples, as the power dissipated into the sample increases linearly with the spring

Nanometer-resolved mechanical properties around GaN crystal surface steps

• Jörg Buchwald,
• Marina Sarmanova,
• Bernd Rauschenbach and
• Stefan G. Mayr

Beilstein J. Nanotechnol. 2014, 5, 2164–2170, doi:10.3762/bjnano.5.225

• spring constant of 39 N/m. The second resonance mode was used for further analysis. The reduced Young’s modulus was measured by using a reference approach with three reference samples: fused silica (M = 75 GPa), silicon (M = 165 GPa) and sapphire (M = 433 GPa), which were demonstrated to be sufficient

Modification of a single-molecule AFM probe with highly defined surface functionality

• Fei Long,
• Bin Cao,
• Ashok Khanal,
• Shiyue Fang and
• Reza Shahbazian-Yassar

Beilstein J. Nanotechnol. 2014, 5, 2122–2128, doi:10.3762/bjnano.5.221

• spring constant is 10 pN/nm and tip curvature is 2 nm. The Au-coated AFM probes (CSG10/Au) were gifts from NT-MDT with 2.5 nm adhesive Ti layer and 35 nm Au layer, the nominal spring constant is 110 pN/nm and tip curvature is 35 nm. The aminopropylsilane-coated glass slides (C18-5131-M20) were purchased

• . When the probe is retracted, the force to break the hydrogen bonds should be detectable. The force spectroscopy experiments were carried out in contact mode at room temperature in isopropanol. The spring constant of the AFM probes were calibrated by using the thermal noise method [30]. The measured

Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt

• Peter Robaschik,
• Pablo F. Siles,
• Daniel Bülz,
• Peter Richter,
• Manuel Monecke,
• Michael Fronk,
• Svetlana Klyatskaya,
• Daniel Grimm,
• Oliver G. Schmidt,
• Mario Ruben,
• Dietrich R. T. Zahn and
• Georgeta Salvan

Beilstein J. Nanotechnol. 2014, 5, 2070–2078, doi:10.3762/bjnano.5.215

• performed in AC tapping mode, which guarantees minimal contact between the AFM probe and the organic film. Ultra sharp (4–10 nm radius) Olympus cantilevers allowed high sensitivity measurements. cs-AFM measurements were performed in contact mode using special Pt-coated Si cantilevers with a spring constant

Dissipation signals due to lateral tip oscillations in FM-AFM

• Michael Klocke and
• Dietrich E. Wolf

Beilstein J. Nanotechnol. 2014, 5, 2048–2057, doi:10.3762/bjnano.5.213

• oscillation of a harmonic spring with the spring constant kz. The mass mz has to be chosen such that the frequency matches the frequency of the cantilever [24]. The internal damping of the cantilever motion is experimentally compensated by a driving force. There exist sophisticated models that describe the

• and φ the torsional angle of the cantilever. Denoting the moment of inertia of the cantilever by J and the torsional spring constant by kφ, the equation of motion for φ without the interaction with the substrate would be , which is in agreement with Equation 2, if one identifies kx = kφ/r2 and mx = J

• parameter set Before we study the influence of single parameters, we want to get a quick overview, what can actually be expected. This is obtained by a Monte Carlo sampling of the parameter space, in which we chose combinations of parameters randomly within a reasonable range. The normal spring constant kz

Hydrophobic interaction governs unspecific adhesion of staphylococci: a single cell force spectroscopy study

• Nicolas Thewes,
• Peter Loskill,
• Philipp Jung,
• Henrik Peisker,
• Markus Bischoff,
• Mathias Herrmann and
• Karin Jacobs

Beilstein J. Nanotechnol. 2014, 5, 1501–1512, doi:10.3762/bjnano.5.163

• , MA, USA) with a nominal spring constant of 0.03 N/m. After the cantilevers were cleaned in an air plasma, they were vertically immersed into a solution of 4 mg/mL dopamine hydrochloride (99%, Sigma-Aldrich) in 10 mM TRIS-buffer (pH 7.9 at 22 °C) and kept at 4 °C in the fridge for 50 min. The

• ), mounted onto the AFM. Subsequently, it was calibrated in liquid by using the thermal tune technique [23], which allows for the calculation of the individual spring constant of the cantilever. Afterwards, holder and cantilever were placed into a micromanipulation system (Narishige Group, Japan). The

• recorded during the approach and retraction of the bacterial probe to and from the surface. The deflection data was converted into force values by means of the spring constant of the cantilever, determined as described above. The approach is performed until a certain repulsive force is reached (“force

A nanometric cushion for enhancing scratch and wear resistance of hard films

• Katya Gotlib-Vainshtein,
• Olga Girshevitz,
• Chaim N. Sukenik,
• David Barlam and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2014, 5, 1005–1015, doi:10.3762/bjnano.5.114

• beams) enables simultaneous work using both beams. Atomic force microscopy (AFM). All scanning probe microscopy was done using an ICON instrument (Bruker AXS SAS). The deflection sensitivity of each probe was measured by pressing the probe on a hard surface and spring constant was calibrated by the

• information was obtained via the torsional deflection of the cantilever with the scan direction running perpendicular to the major axis of the cantilever. Quantitative values of the frictional force were made as per reference [51]. A silicon nitride "A" shaped cantilever (normal spring constant 0.32 N/m) with

Calibration of quartz tuning fork spring constants for non-contact atomic force microscopy: direct mechanical measurements and simulations

• Jens Falter,
• Marvin Stiefermann,
• Gernot Langewisch,
• Philipp Schurig,
• Hendrik Hölscher,
• Harald Fuchs and
• André Schirmeisen

Beilstein J. Nanotechnol. 2014, 5, 507–516, doi:10.3762/bjnano.5.59

• -Leopoldshafen, Germany 10.3762/bjnano.5.59 Abstract Quartz tuning forks are being increasingly employed as sensors in non-contact atomic force microscopy especially in the “qPlus” design. In this study a new and easily applicable setup has been used to determine the static spring constant at several positions

• prefactor and therefore directly suffer from an inaccurate determination of the spring constant. Here we present an experimental procedure that allows for the direct measurement of the stiffness of a tuning fork sensor in the “qPlus” design with standard lab equipment. Our results reveal that a large spread

• origin is shifted to the position of zero stress onset inside the tuning fork base and torsional effects are included as well. Comparison with experimental spring constant data still show that the spring constant is overestimated by FEM and beam formula. This effect is attributed to a small but not

The softening of human bladder cancer cells happens at an early stage of the malignancy process

• Jorge R. Ramos,
• Joanna Pabijan,
• Ricardo Garcia and
• Malgorzata Lekka

Beilstein J. Nanotechnol. 2014, 5, 447–457, doi:10.3762/bjnano.5.52

• silicon nitride cantilevers terminated with a silicon tip (MLCT-C, Bruker, USA). Those cantilevers are characterized by a nominal spring constant k = 0.01 N/m while the length of the tip length is about 3 µm long, with a half-angle of 20° and a radius of 20 nm. The sensitivity of the photodiode was

Exploring the complex mechanical properties of xanthan scaffolds by AFM-based force spectroscopy

• Hao Liang,
• Guanghong Zeng,
• Yinli Li,
• Shuai Zhang,
• Huiling Zhao,
• Lijun Guo,
• Bo Liu and
• Mingdong Dong

Beilstein J. Nanotechnol. 2014, 5, 365–373, doi:10.3762/bjnano.5.42

• experiments were performed after 15 min of stabilization. Atomic force microscopy AFM imaging: AFM measurements were conducted on a commercial Agilent AFM/STM 5500 microscope (Agilent Technologies, USA) in contact mode. Nitride silicon cantilevers (OMCL-TR400PSA-1) with a spring constant of 0.02 N/m and a

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

• the cantilever spring constant, k* the contact stiffness, γ* the contact damping constant, and the dimensionless contact damping constant. With the above specified boundary conditions the solution further simplifies to with the following constants for the two configurations: and with M± = sin αL cosh

• length L = 225.03 µm, width w = 30.00 µm, and thickness T = 4.89 µm. With mass density ρSi = 2329.00 kg/m3 and Young’s modulus ESi = 130.00 GPa, the cantilever’s spring constant was calculated as kc = 10.00 N/m. Using these parameters and considering ηair = 2.50 s−1 in Equation 1, the first two

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

• motion of the mth eigenmode where k(m), Q(m), ω(m), and z(m) are the spring constant, quality factor, natural frequency and position of the mth eigenmode. The term FD stands for the external driving force where the subscript without brackets, n, indicates the harmonic number. Note that here ωn = nω

The role of surface corrugation and tip oscillation in single-molecule manipulation with a non-contact atomic force microscope

• Christian Wagner,
• Norman Fournier,
• F. Stefan Tautz and
• Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 202–209, doi:10.3762/bjnano.5.22

• determined by the softer spring S (surface corrugation) and L can be considered as rigid, except for α0 close to 90°, where diverges while remains finite. The total spring constant of the system becomes This expression reflects the basic properties of the correction term Δcorr(α0). Firstly, we find that

Influence of the adsorption geometry of PTCDA on Ag(111) on the tip–molecule forces in non-contact atomic force microscopy

• Gernot Langewisch,
• Jens Falter,
• André Schirmeisen and
• Harald Fuchs

Beilstein J. Nanotechnol. 2014, 5, 98–104, doi:10.3762/bjnano.5.9

• atomic force microscope (Omicron LT-SPM) that was operated in frequency-modulation mode [11] under ultrahigh vacuum conditions and at a temperature of ≈5 K using a tuning fork sensor (resonance frequency f0 = 24640 Hz, spring constant k ≈ 2000 N/m) in the qPlus design [12]. The amplitude of the sensor

Exploring the retention properties of CaF₂ nanoparticles as possible additives for dental care application with tapping-mode atomic force microscope in liquid

• Matthias Wasem,
• Joachim Köser,
• Sylvia Hess,
• Enrico Gnecco and
• Ernst Meyer

Beilstein J. Nanotechnol. 2014, 5, 36–43, doi:10.3762/bjnano.5.4

• by tip–sample interactions. If the cantilever has a normal spring constant k and is driven sinusoidally with the amplitude A0 and drive frequency ω0, we can calculate the average power dissipated by tip–sample interactions as where A is the damped amplitude at the given set point, Qcant the quality

Surface assembly and nanofabrication of 1,1,1-tris(mercaptomethyl)heptadecane on Au(111) studied with time-lapse atomic force microscopy

• Tian Tian,
• Burapol Singhana,
• Lauren E. Englade-Franklin,
• Xianglin Zhai,
• T. Randall Lee and
• Jayne C. Garno

Beilstein J. Nanotechnol. 2014, 5, 26–35, doi:10.3762/bjnano.5.3

• accomplished with silicon nitride tips, which had an average spring constant of 0.5 N/m (Bruker Instruments, Camarillo, CA). Digital images were processed and analyzed with Gwyddion v.2.25 software [43]. Analysis of surface coverage was accomplished by manually selecting a threshold value to convert images to

Noise performance of frequency modulation Kelvin force microscopy

• Heinrich Diesinger,
• Dominique Deresmes and
• Thierry Mélin

Beilstein J. Nanotechnol. 2014, 5, 1–18, doi:10.3762/bjnano.5.1

• merit factor is If it is assumed that the maximum oscillation amplitude D0 cannot exceed a certain fraction of z and hence is proportional to it, it reduces to Furthermore, a relation has to be respected between minimum tip–sample distance z and spring constant k to avoid snap to contact. Figure 17

• shows the tip in the attractive part of the van-der-Waals interaction. The force gradient in this field must not exceed the spring constant to avoid snap to contact. We take the attractive range of a Lennard-Jones type of potential The force gradient is proportional to the second derivative: To avoid

•  49 for the relation between z and k yields Unsurprisingly, for the case of dominating sensor noise, maximization of the merit factor requires minimizing the sensor noise. Both merit factors, Equation 50 and Equation 55, suggest downsizing both the probe spring constant and mass. If one considers f0

Peak forces and lateral resolution in amplitude modulation force microscopy in liquid

• Horacio V. Guzman and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2013, 4, 852–859, doi:10.3762/bjnano.4.96

• of motion for the microcantilever–tip system is approximated by using the point-mass model [25], where m is the effective cantilever mass that includes the added mass of the fluid, and ω0, Q, k and Fts are, respectively, angular resonant frequency, quality factor, spring constant and tip–sample

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• . Instrumentation Schematics of INI and AFM instruments are shown in Figure 2. Table 1 gives a comparison of their capabilities and characteristics. For INI, a calibrated force is applied to the indenter tip, which in turn is constrained with a vertical spring. The lateral spring constant can be considered infinite

• improved, and the accessible dynamic force range is enhanced since each harmonic is associated with its own characteristic spring constant. Investigation of a material over a wide range of frequencies also gives a sharper topographic contrast since some materials, which may yield under the tip force, are

• the sample in the AFM (Bruker, multimode). Prior to the experiment, the cantilever spring constant and the deflection sensitivity were determined with the Nanoscope software (former from the thermal noise and the latter by measuring the deflection of the cantilever with the displacement on a hard

Atomic force microscopy recognition of protein A on Staphylococcus aureus cell surfaces by labelling with IgG–Au conjugates

• Elena B. Tatlybaeva,
• Hike N. Nikiyan,
• Alexey S. Vasilchenko and
• Dmitri G. Deryabin

Beilstein J. Nanotechnol. 2013, 4, 743–749, doi:10.3762/bjnano.4.84

• ) operated in contact mode. V-shaped silicon nitride cantilevers MSCT-AUNM from Veeco Instruments Inc. with a spring constant of 0.01 N/m were used. The typical radius of the MSCT-AUNM tip is approx. 10 nm, which is comparable to the size of the gold conjugates utilized in immunolabelling experiments

AFM as an analysis tool for high-capacity sulfur cathodes for Li–S batteries

• Renate Hiesgen,
• Seniz Sörgel,
• Rémi Costa,
• Linus Carlé,
• Ines Galm,
• Natalia Cañas,
• Brigitta Pascucci and
• K. Andreas Friedrich

Beilstein J. Nanotechnol. 2013, 4, 611–624, doi:10.3762/bjnano.4.68

• µm length) and an identical AFM tip (PPP-NCHPt, NanoAndMore GmbH, spring constant: 30–50 N/m). Images measured in PeakForce-TUNA™ mode were not included in the statistical evaluations. The stiffness values of sulfur base-materials were out of the range recommended for analysis with the tip

Molecular dynamics simulations of mechanical failure in polymorphic arrangements of amyloid fibrils containing structural defects

• Hlengisizwe Ndlovu,
• Alison E. Ashcroft,
• Sheena E. Radford and
• Sarah A. Harris

Beilstein J. Nanotechnol. 2013, 4, 429–440, doi:10.3762/bjnano.4.50

• simulation were used to ensure that the trajectories sampled different areas of phase space. The SMD simulations all used a spring constant of 500 pN/Å with a constant pulling velocity of 0.01 Å/ps unless otherwise stated. The duration of the SMD simulations were 4 ns for “stretch”, “slide” and “shear

Optimal geometry for a quartz multipurpose SPM sensor

• Julian Stirling

Beilstein J. Nanotechnol. 2013, 4, 370–376, doi:10.3762/bjnano.4.43

• excited at or near one of its eigenfrequencies, properties such as the Q factor, eigenfrequencies, effective spring constant [1] and other geometrical properties [2] of the eigenmodes become important. AFM and LFM sensors have evolved from gold foil with diamond tip [3] and bent tungsten wires [4

• atomic-resolution imaging the effective spring constant of the excited eigenmode should be low [13]. However, as the spring constant normal to the surface lowers, the risk of the probe snapping to contact with the surface increases. This produces a problem for combined AFM/LFM using the principal and

• first torsional eigenmode of a cantilever, as the torsional mode can have an effective spring constant of up to approximately two orders of magnitude higher than the principal mode [10]. This results in a difficult tradeoff. To avoid snap to contact, the following condition must be satisfied [14]: where

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

• drive force and a time-dependent tip–surface force where the dot denotes differentiation with respect to time, ω0, Q and kc are the mode’s resonance frequency, quality factor and spring constant respectively, and h is the static equilibrium position of the tip above the surface. One should note that the

• cantilever (Bruker MPP-11120) was calibrated by a noninvasive thermal method [30] and had a resonance frequency of f0 = 229.802 kHz, a quality factor of Q = 396.9 and a spring constant of kc = 16.0 N m−1. The slow surface approach velocity was 2 nm s−1. PS (Mw = 280 kDa, Sigma-Aldrich) and PMMA (Mw = 120 kDa

• , Sigma-Aldrich) were spin-cast from toluene solution with a concentration of 0.53 %wt at a ratio of 3:1 (PMMA:PS). The sample was scanned in a Bruker Multimode 2 AFM system with a cantilever BS 300Al-G (Budget Sensors) having a resonance frequency f0 = 343.379 kHz, quality factor Q = 556.9 and spring

High-resolution nanomechanical analysis of suspended electrospun silk fibers with the torsional harmonic atomic force microscope

• Mark Cronin-Golomb and
• Ozgur Sahin

Beilstein J. Nanotechnol. 2013, 4, 243–248, doi:10.3762/bjnano.4.25

• measuring the quasi-static force from vertical deflections while monitoring the torsional deflection signal. Note that the same force acts on both vertical and torsional modes. Therefore, after calibrating the vertical spring constant, the gain of the torsional mode can be determined by comparing time

• various physical models to obtain parameters describing the mechanical response of the sample. In the case of electrospun silk fibers, we have calculated both the local elastic modulus and the local spring constant values. The elastic modulus is calculated according to the Derjaguin–Muller–Toporov (DMT

• ) model and the spring constant (stiffness) is calculated by fitting the unloading portion of the force–distance curve with a straight line. For the DMT model, we used a tip radius of 7 nm, which is characterized by blind reconstruction from a sample with sharp edges. Our calculations assumed that the