Multifunctional probe microscope for facile operation in ultrahigh vacuum

Howald, L.; Meyer, Ernst; Lüthi, R.; Haefke, H.; Overney, René M.; Rudin, H.; Güntherodt, H.‐J.

doi:10.1063/1.109732

Cited by 176 publications

(91 citation statements)

References 9 publications

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“…The set-up of our SFM is based on the beam-deflection principle [28] and equals the design of Howald et al [29]. The dynamic mode of the SFM is realized as described in [30] and further characterized in [31,32].…”

Section: Imaging Modesmentioning

confidence: 99%

Imaging nanoclusters in theconstant height modeof the dynamic SFM

et al. 2006

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For the first time, high quality images of metal nanoclusters which were recorded in the constant height mode of a dynamic scanning force microscope (dynamic SFM) are shown. Surfaces of highly ordered pyrolytic graphite (HOPG) were used as a test substrate since metal nanoclusters with well defined and symmetric shapes can be created by epitaxial growth. We performed imaging of gold clusters with sizes between 5 and 15 nm in both scanning modes, constant f mode and constant height mode, and compared the image contrast. We notice that clusters in constant height images appear much sharper, and exhibit more reasonable lateral shapes and sizes in comparison to images recorded in the constant f mode. With the help of numerical simulations we show that only a microscopically small part of the tip apex (nanotip) is probably the main contributor for the image contrast formation. In principle, the constant height mode can be used for imaging surfaces of any material, e.g. ionic crystals, as shown for the system Au/NaCl(001).

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Section: Imaging Modesmentioning

confidence: 99%

Imaging nanoclusters in theconstant height modeof the dynamic SFM

et al. 2006

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“…The setup of our SFM is described in references. [37][38][39][40][41] Dynamic SFM measures the change in frequency, ⌬f, that appears due to the interaction of the oscillating tip with the surface. 11,12 In order to measure the detuning with high precision and stability, we used a digital demodulator ͑EasyPLL, nanoSurf AG͒.…”

Section: B Scanning Force Imagingmentioning

confidence: 99%

Imaging the real shape of nanoclusters in scanning force microscopy

Pakarinen

Barth

Foster

et al. 2008

Journal of Applied Physics

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A quantitative comparison between experiment and theory is given for the constant height mode imaging of metal nanoclusters in dynamic scanning force microscopy. We explain the fundamental mechanisms in the contrast formation with the help of the system Pd/MgO͑001͒. The comparison shows that the shape and size of nanoclusters are precisely imaged due to the sharpness of the tip's last nanometer. This quantitative comparison proves our previously proposed model for the contrast formation.

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“…The NaCl(001) sample surface was cleaved in a ultrahigh vacuum (UHV) chamber and analyzed using a home-built AFM 18 Atomic-scale friction force loops measured on NaCl(001) in UHV at room temperature with (dark blue) and without (light blue) lateral vibrations. Rs = vst is the cantilever position averaged over the vibrations.…”

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confidence: 99%

Lateral vibration effects in atomic-scale friction

Roth

Fajardo

Mazo

et al. 2014

Applied Physics Letters

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The influence of lateral vibrations on the stick-slip motion of a nanotip elastically pulled on a flat crystal surface is studied by atomic force microscopy (AFM) measurements on a NaCl(001) surface in ultra-high vacuum. The slippage of the nanotip across the crystal lattice is anticipated at increasing driving amplitude, similarly to what is observed in presence of normal vibrations. This lowers the average friction force, as explained by the Prandtl-Tomlinson model with lateral vibrations superimposed at finite temperature. Nevertheless, the peak values of the lateral force, and the total energy losses, are expected to increase with the excitation amplitude, which may limit the practical relevance of this effect.Developing strategies for lowering friction is a key issue for proper functioning of micro-and nanoelectromechanical systems (MEMS and NEMS). In this context, traditional lubricants cannot be used, since the viscosity of mineral oils dramatically increases when the lubricant molecules are confined into nanometer-sized interstices 1 . Different approaches, such as mechanical excitations, need to be explored. Ultrasonic vibrations have been used for years to modify the frictional behavior of materials at a macroscopic scale 2 and their application at the nanoscale looks quite promising 3-7 . Here, we are particularly interested in sharp asperities sliding on atomically flat surfaces. In this case, exciting mechanical resonances of the nano-junctions formed while sliding can be a valid method to reduce friction. This was shown by Socoliuc et al.5 in atomic-scale AFM experiments on alkali halide surfaces in ultra-high vacuum (UHV) and by Lantz et al.6 , who succeeded in preventing the abrasive wear of a silicon tip sliding over several hundred meters following this strategy. The state of 'dynamic superlubricity' so-achieved was also exploited to acquire lattice-resolved friction force maps of crystal surfaces without damaging the samples 8 . Note that, in the previous experimental works, the actuation was applied perpendicular to the sliding plane. Friction reduction was also predicted theoretically when mechanical oscillations are induced parallel to this plane 9 . However, although this effect was observed in a series of macroscopic measurements based on a tribometer 10 , the variation of the friction features on the atomic scale has not been documented so far.In this work we present AFM measurements in UHV complementing the results in Ref. 5, where the effect of normal excitations was investigated by applying an ac voltage between the tip and a counter electrode on the backside of an insulating KBr(001) surface. Here, lateral vibrations of the probing tip are induced by shaking a piezo-element attached to the cantilever sensor of FIG. 1. Thermal noise power spectrum of the normal (blue curve) and torsional vibrations (red curve) of the AFM sensor used in the experiment in contact with a NaCl(001) surface in UHV.the AFM at a frequency corresponding to the torsional resonance of the cantilever in contact ...

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Multifunctional probe microscope for facile operation in ultrahigh vacuum

Cited by 176 publications

References 9 publications

Imaging nanoclusters in theconstant height modeof the dynamic SFM

Imaging nanoclusters in theconstant height modeof the dynamic SFM

Imaging the real shape of nanoclusters in scanning force microscopy

Lateral vibration effects in atomic-scale friction

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