Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

• Adam Sweetman and
• Andrew Stannard

Beilstein J. Nanotechnol. 2014, 5, 386–393, doi:10.3762/bjnano.5.45

• transferred into the scan head and left to cool before imaging. Commercial qPlus sensors from Omicron with electrochemically etched tungsten wire glued to one tine of the tuning fork were introduced into the scan head without any further preparation. We typically recorded resonant frequencies of f0 ≈ 25 kHz

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

• strength to allow the lifting of the molecule from the surface up to the point of its complete removal. Recording the frequency shift Δf(z) of the qPlus tuning fork during the removal of the molecule, we have previously succeeded in reconstructing the junction structure throughout the manipulation process

• main factors that have been omitted from the initial model: i) the atomic corrugation of the surface, ii) the elasticity of the tip material, and iii) the finite amplitude of the qPlus tuning fork oscillation. Here we take a step towards more realistic force-field simulations of single-molecule

• the intrinsic stiffness of the qPlus tuning fork (kqPlus) is much higher than the typical strengths of single atomic bonds, it can be used to test processes of single-bond ruptures reliably (in practice the overall success of such tests is limited by the stiffness of the metallic tip that is employed

Manipulation of nanoparticles of different shapes inside a scanning electron microscope

• Boris Polyakov,
• Sergei Vlassov,
• Leonid M. Dorogin,
• Jelena Butikova,
• Mikk Antsov,
• Sven Oras,
• Rünno Lõhmus and
• Ilmar Kink

Beilstein J. Nanotechnol. 2014, 5, 133–140, doi:10.3762/bjnano.5.13

• . Measurements were performed inside a scanning electron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models

• ) equipped with a custom-made force sensor. The force sensor was made by gluing an electrochemically sharpened tungsten wire or commercial AFM cantilever with a sharp tip (Nanosensor ATEC-CONT cantilevers C = 0.2 N/m) to one prong of a commercially available quartz tuning fork (QTF). The tip of ATEC-CONT

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

k-space imaging of the eigenmodes of sharp gold tapers for scanning near-field optical microscopy

• Martin Esmann,
• Simon F. Becker,
• Bernard B. da Cunha,
• Jens H. Brauer,
• Ralf Vogelgesang,
• Petra Groß and
• Christoph Lienau

Beilstein J. Nanotechnol. 2013, 4, 603–610, doi:10.3762/bjnano.4.67

• is controlled using a tuning fork-based force sensor in a noncontact-mode atomic force microscope (AFM). This microscope is a modified version of the setup described in [10]. The taper probe is attached to one prong of a quartz tuning fork that oscillates with a peak-to-peak amplitude of 1 nm. The

• cover slip is mounted onto a three-axis piezoelectric stage (PI P-363.3CD). This allows us to slowly approach the sample to the taper over a distance of several hundreds of nanometers in steps of 30 pm until the tuning fork starts to be damped by tip–sample interactions. The damping occurs on a length

Optimal geometry for a quartz multipurpose SPM sensor

• Julian Stirling

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

• ] respectively, into a wide range of specialised sensors. The most common NC-AFM sensors: silicon microcantilvers [5], and quartz sensors such as the qPlus sensor (tuning fork) [6] or KolibriSensor® [7], have all been used for combined AFM/STM [7][8][9]. Combined AFM/LFM sensors have been constructed from

• silicon cantilevers, by exciting torsional modes to generate the lateral motion needed for the LFM [10]. The qPlus sensor has been used as an LFM by rotating the tip on the end of the quartz tuning fork [11], but no combined AFM/LFM qPlus system has been developed due to the magnitude of the torsion

• closest commercially available sensor is a double-ended tuning fork available from Statek (DETF Force Sensor, http://www.statek.com). By fixing the bottom tine it is possible to reproduce the required symmetry. However, these sensors are too large for most commercial qPlus systems with a total width of

Determining cantilever stiffness from thermal noise

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

Beilstein J. Nanotechnol. 2013, 4, 227–233, doi:10.3762/bjnano.4.23

• force microscopy (NC-AFM) based on cantilever or tuning fork force sensors. We recently demonstrated how Equation 1 defines the ultimate limit of signal detection for an NC-AFM measurement performed under ultrahigh vacuum (UHV) conditions [6]. Although most NC-AFM systems are operated with cantilevers

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

• forces in liquids on clean, hard surfaces, such as mica, that allow asp ≈ λ with a probe that is much softer than the tuning fork [2]. In vacuum, strong attractive forces cause the tip to snap into the surface when oscillation amplitudes are small. From the data in Table 1, we must also entertain the

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

• and molecular interactions [6][7]. As with all forms of AFM, image resolution and force measurements ultimately depend on the structure of the last few angstroms of the tip apex [1][2][4][6][7][8][9]. The qPlus sensor is unusual for an AFM sensor in that it is constructed from a quartz tuning fork and

• tine of the tuning fork. The dynamics of the tip bending have not been included as the model is only of interest at the eigenfrequencies of the loaded tine. The tip protrudes H from the tine giving the tip a total length of H + tTF. The axis of rotation is located at the center of the join between the

• centre of mass of the tip to the axis of tip rotation. The tine of the tuning fork is assumed to be clamped at the left-hand side. (b) Geometrical diagram of the tip motion as the cantilever deforms. Note the two ψ angles are not identical in this diagram as θ is too large due to the exaggerated

Characterization of the mechanical properties of qPlus sensors

• Jan Berger,
• Martin Švec,
• Martin Müller,
• Martin Ledinský,
• Antonín Fejfar,
• Pavel Jelínek and
• Zsolt Majzik

Beilstein J. Nanotechnol. 2013, 4, 1–9, doi:10.3762/bjnano.4.1

• . Keywords: AFM; Cleveland’s method; cross talk; force; qPlus; stiffness; STM; thermal noise; tuning fork; Introduction The invention of scanning tunneling microscopy [1] and atomic force microscopy (AFM) [2] opened new horizons in characterization and modification of surfaces and nanostructures. STM is

• nowadays (see, e.g., [7][9][17][18][19][20][21]). The heart of the qPlus-based AFM/STM microscope is a tuning fork with one prong fixed and the other, with a metallic tip positioned at the very end, freely oscillating. The variation of the resonant frequency of the prong reflects directly the interaction

• sensors with prong lengths varying from 1.8 to 2.4 mm. Due to the variation of the length and of the mass of the attached tips, the resonant frequency altered between 25 and 60 kHz. For commercial sensors, the tip was attached on the side of the prong, effectively shortening the tuning fork. Consequently

Spring constant of a tuning-fork sensor for dynamic force microscopy

• Dennis van Vörden,
• Manfred Lange,
• Merlin Schmuck,
• Nico Schmidt and
• Rolf Möller

Beilstein J. Nanotechnol. 2012, 3, 809–816, doi:10.3762/bjnano.3.90

• tuning fork in qPlus configuration. The simple calculation for a rectangular cantilever is compared to the values obtained by the analysis of the thermal excitation and by the direct mechanical measurement of the force versus displacement. To elucidate the difference, numerical simulations were performed

• taking account of the real geometry including the glue that is used to mount the tuning fork. Keywords: atomic force microscopy; finite element method; spring constant; thermal fluctuation; tuning fork; Introduction Quartz tuning forks provide excellent self-sensing probes in scanning probe microscopy

• , offering several advantages compared to the standard microfabricated silicon-based cantilevers [1][2]. Frequency-modulation atomic force microscopy (FM-AFM) with a tuning-fork sensor has had a major impact on fundamental and scientific research, e.g., by resolving the structure of a molecule [3] or even

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

• fact, in many cases atomic-resolution images are only obtained after the tip has been deliberately crashed into the surface, implying that the tip apex is formed from surface species [1][2]. The development of NC-AFM based on a quartz tuning fork (qPlus sensor) instead of a silicon cantilever has led

• to more freedom in choosing the tip material, as a tip can be manually attached to the tuning-fork prong [5]. However, the problem of keeping the tip apex free of contaminants remains. One approach to deal with the problem of tip–apex control is to employ a tip material that is easy to prepare and

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

• functionalized tip, that is, with a CO molecule attached to the tip apex acting as a supertip [60]. Most of the mentioned studies were based on a technical improvement consisting of the use of a tuning fork of the qPlus sensor type [61]. This sensor is an AFM tip that is fixed to one branch of a quartz tuning

• fork and provides a stiff probe capable of being approached close enough to the sample without touching the surface [62]. When the probe is oscillating above the sample, one of the characteristics of an experimental FM-AFM setup is the presence of several feedback loops to pilot the probe based on the

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

• .3.28 Abstract We present the results of simultaneous scanning-tunneling and frequency-modulated dynamic atomic force microscopy measurements with a qPlus setup. The qPlus sensor is a purely electrical sensor based on a quartz tuning fork. If both the tunneling current and the force signal are to be

• interferometric deflection. Keywords: AFM; cross-talk; current; dissipation; force; qPlus; STM; tuning fork; Introduction The invention of scanning probe techniques, in particular scanning tunneling microscopy (STM) [1] and atomic force microscopy (AFM) [2], had a tremendous impact on our understanding of the

• tuning fork was shortened in order to reach higher sensitivity (charge produced by deflection) [35], which allows us to reach lower amplitudes. The interaction force between the tip and surface atoms was calculated from the measured frequency-shift data by means of the Sader formula [36]. The tunneling

Analysis of force-deconvolution methods in frequency-modulation atomic force microscopy

• Joachim Welker,
• Esther Illek and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 238–248, doi:10.3762/bjnano.3.27

• (maximum attractive force). Therefore, we also compare the deviation from the model values: To calculate the frequency shift we chose a tuning fork sensor in the qPlus design [13] with a spring constant of k = 1800 N/m and a resonance frequency of f0 = 32768 Hz. This sensor can operate with very small

A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope

• Manfred Lange,
• Dennis van Vörden and
• Rolf Möller

Beilstein J. Nanotechnol. 2012, 3, 207–212, doi:10.3762/bjnano.3.23

• process can be understood as a hysteresis of forces between approach and retraction of the tip. In this paper, we present the direct measurement of the whole hysteresis loop in force-spectroscopy curves at 77 K on the PTCDA/Ag/Si(111) √3 × √3 surface by means of a tuning-fork-based NC-AFM with an

• 77 K with a home-built low-temperature tuning-fork-based AFM (LT-TF-AFM) [9]. When a conductive sample is used, scanning tunneling microscopy (STM) and FM-AFM measurements may be combined. The use of a tuning fork as a sensor allows an oscillation amplitude in the subnanometer regime to be used, due

• width of the hysteresis loop is about 3–4 Å, hence larger than the oscillation amplitude of the tuning fork. The width corresponds to a geometric change in the tip–sample configuration, which is probably caused by the lifting of the molecule. A schematic representation of the process is displayed in

qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

• Maximilian Schneiderbauer,
• Daniel Wastl and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 174–178, doi:10.3762/bjnano.3.18

• fork. The qPlus sensor [8] is based on a quartz tuning fork, in which one prong is attached to a carrier substrate. The large spring constant of the qPlus, k = 1800 Nm−1, allows one to overcome the snap-to-contact-problem in small-amplitude operation [9]. In this mode, the qPlus setup is customized for

• acquisition times. To benchmark our setup, we reduced the magnetic moment of the tip by attaching a commercial MFM cantilever tip (NanoWorld Pointprobe MFMR, coated with approx. 40 nm cobalt alloy) onto a qPlus sensor. This has been done before in tuning-fork setups in room-temperature ultrahigh-vacuum

• , magnetically coated silicon cantilevers are used. These cantilevers are produced in large quantity by microfabrication techniques. Typical probe features are spring constants on the order of 10 Nm−1 and resonance frequencies of about 100 kHz. Another type of force sensor is made from a quartz (SiO2) tuning

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

• 1200 °C, and then slow cooling from 900 °C to room temperature before being placed into the scan head. We introduced commercial qPlus sensors (Omicron GmbH), with an electrochemically etched tungsten wire attached to one tine of the tuning fork, into the scan head without any ex situ tip treatment. The

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

• . If the tip-sample distance reaches the range of interatomic forces or the tunneling regime, the walker is switched off and the scan is performed by the x, y and z piezos. An additional excitation piezo orientated along z excites the tuning fork at resonance. The tuning fork sensor is presented in

• setup, one prong of the tuning fork is glued onto the carrier. A Pt0.9Ir0.1 wire, 250 μm in diameter, is attached to the other prong as a tip. The use of a non-conducting glue electrically insulates the tip from the tuning fork and prevents cross talk. Due to the fixed prong and the additional mass of

• the tip at the other prong, the resonance frequency drops to about 22 kHz. The tuning fork is driven by the excitation piezo. Due to the piezo electric effect, the signal of the resonance frequency can be detected at the electrodes of the tuning fork. The amplitude of the signal is proportional to the