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Search for "feedback" in Full Text gives 217 result(s) in Beilstein Journal of Nanotechnology. Showing first 200.

Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes

  • Gemma Rius,
  • Matteo Lorenzoni,
  • Soichiro Matsui,
  • Masaki Tanemura and
  • Francesc Perez-Murano

Beilstein J. Nanotechnol. 2015, 6, 215–222, doi:10.3762/bjnano.6.20

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  • (<20 nm), to ensure a close tip–surface distance and the set point amplitude is routinely set to 80% of the free amplitude for imaging when the feedback is active. Under these conditions, attractive forces dominate and, in consequence, it can be inferred that the AFM is operated in non-contact mode. In
  • current experiments we focus on the definition of line patterns. Prior to patterning, the AFM control feedback is disabled and the required voltage is applied. However, in order to keep a constant tip–surface distance, previously the surface inclination with respect to the X–Y piezo-scanning plane is
  • present paper. As far as the tips did not make contact with the surface (either by particle contamination or the surface or problems with feedback loop control) we did not observe tip wear. Discussion In Figure 6 the main results of the kinetics study of LAO-AFM are summarized. Figure 6a shows the line
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Published 19 Jan 2015

Kelvin probe force microscopy in liquid using electrochemical force microscopy

  • Liam Collins,
  • Stephen Jesse,
  • Jason I. Kilpatrick,
  • Alexander Tselev,
  • M. Baris Okatan,
  • Sergei V. Kalinin and
  • Brian J. Rodriguez

Beilstein J. Nanotechnol. 2015, 6, 201–214, doi:10.3762/bjnano.6.19

Graphical Abstract
  • , become complicated by feedback artefacts and stray capacitance even in vacuum [33][34][35]. In ambient environments, the interpretation of surface potential values increases in complexity due to the possible shielding of the surface by mobile adsorbates and the presence of a thin water layer, resulting
  • previously reported [40][41][42][43]. In general, open loop-KPFM does not require the application of a DC bias via a feedback loop and can be performed by utilizing either (i) both AC voltage and DC bias (referred to here as open loop bias spectroscopy, OLBS) [44], or (ii) AC voltage alone (referred to here
  • second harmonic cantilever amplitude (Aω and A2ω) and phase (θω and θ2ω) using lock-in techniques. Equation 2 predicts a linear dependence of Fω with respect to the probe–sample DC bias, which is minimized when Vdc = Vcpd. KPFM employs this principle via a feedback loop to minimize Aω. Depending on the
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Published 19 Jan 2015

Tunable light filtering by a Bragg mirror/heavily doped semiconducting nanocrystal composite

  • Ilka Kriegel and
  • Francesco Scotognella

Beilstein J. Nanotechnol. 2015, 6, 193–200, doi:10.3762/bjnano.6.18

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  • exploited in several types of devices, such as distributed feedback lasers [11][12][13][14][15], sensors [16][17], absorption enhancement for photovoltaics [18] or in dye-sensitized solar cells [19][20][21]. Furthermore, nanoparticle-based photonic crystals have been employed for switching applications [22
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Published 16 Jan 2015

Accurate, explicit formulae for higher harmonic force spectroscopy by frequency modulation-AFM

  • Kfir Kuchuk and
  • Uri Sivan

Beilstein J. Nanotechnol. 2015, 6, 149–156, doi:10.3762/bjnano.6.14

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  • formulae for both conservative and dissipative forces. In FM-AFM, a cantilever is oscillated at its resonance frequency using an external driving force and a feedback loop. The motion of the cantilever is often modelled as a driven damped harmonic oscillator with an additional force, Fts, stemming from tip
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Published 13 Jan 2015

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

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  • simultaneously tracking topography. The resonant excitation power needed to keep the second eigenmode at a specific amplitude is mapped, while a phase locked loop (PLL) ensures resonant excitation. Topography feedback deconvolutes material specific effects acting on the second resonance. As the resonant
  • squeeze-film damping of the cantilever, the latter of which is roughly constant while in feedback. We used a thin-film blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) as a sample (PS–PMMA–15M, Bruker AFM probes); its separation into soft and hard domains makes it a widely used standard for
  • contrast for the softer globular areas with no visible effects from the topography feedback. At present, we are uncertain of the source of the apparent contrast inversion at the edges of the globular areas in Figure 4d versus Figure 4a, although it may be due to surface restructuring of the polymer blend
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Published 22 Dec 2014

Advanced atomic force microscopy techniques II

  • Thilo Glatzel,
  • Ricardo Garcia and
  • Thomas Schimmel

Beilstein J. Nanotechnol. 2014, 5, 2326–2327, doi:10.3762/bjnano.5.241

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  • properties [21] are based on the implementation of proportional-integral controllers to give realistic feedback behaviours. Stirling proposed a theoretical model for studying the SPM feedback in the context of control theory providing the possibility to understand and model the performance from SPM systems
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Editorial
Published 03 Dec 2014

Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes – a new strategy for OLED materials

  • Pascal R. Ewen,
  • Jan Sanning,
  • Tobias Koch,
  • Nikos L. Doltsinis,
  • Cristian A. Strassert and
  • Daniel Wegner

Beilstein J. Nanotechnol. 2014, 5, 2248–2258, doi:10.3762/bjnano.5.234

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  • transferred in situ into the cold STM (T = 5 K). All images where taken in constant-current mode. For the tunneling spectra the current I and the differential conductance dI/dV (via lock-in technique, modulation voltage 10–20 mV) were measured simultaneously as a function of sample bias V under open-feedback
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Published 26 Nov 2014

Characterization of 10,12-pentacosadiynoic acid Langmuir–Blodgett monolayers and their use in metal–insulator–metal tunnel devices

  • Saumya Sharma,
  • Mohamad Khawaja,
  • Manoj K. Ram,
  • D. Yogi Goswami and
  • Elias Stefanakos

Beilstein J. Nanotechnol. 2014, 5, 2240–2247, doi:10.3762/bjnano.5.233

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  • concentration of PDA dissolved in chloroform. The surface tension was measured using a paper Wilhelmy plate suspended in the water in the LB trough. The deposition conditions were regulated using surface tension and compression feedback control. This resulted in the formation of a closely packed film at the air
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Published 26 Nov 2014

Patterning a hydrogen-bonded molecular monolayer with a hand-controlled scanning probe microscope

  • Matthew F. B. Green,
  • Taner Esat,
  • Christian Wagner,
  • Philipp Leinen,
  • Alexander Grötsch,
  • F. Stefan Tautz and
  • Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 1926–1932, doi:10.3762/bjnano.5.203

Graphical Abstract
  • contacting and the current feedback loop of the SPM software was opened. The contact to the molecule was established by approaching the tip vertically towards the surface; this approach was effected by downward movement of the hand of the operator. Over the course of HCM the current I flowing through the
  • junction and the frequency shift Δf were displayed on the screen of an oscilloscope and served as feedback signals for the operator. Formation (loss) of the contact was monitored in real time by a sharp increase (decrease) of I (cf. Figure 1b) or a kink in Δf [15][16]. After establishing the contact
  • the tip with the removed PTCDA molecule hanging on its apex towards the Ag(111) surface and applying a voltage pulse of 0.6–1 V. Afterwards the current feedback loop was closed and the manipulation area was scanned in constant current STM mode (a movie that was made of the scanned STM images can be
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Published 31 Oct 2014

Multi-frequency tapping-mode atomic force microscopy beyond three eigenmodes in ambient air

  • Santiago D. Solares,
  • Sangmin An and
  • Christian J. Long

Beilstein J. Nanotechnol. 2014, 5, 1637–1648, doi:10.3762/bjnano.5.175

Graphical Abstract
  • higher modes are excited by using constant drive frequency and amplitude without any feedback (i.e., in ‘open loop’ [2][3]). In such cases, as long as the oscillation is not chaotic, the user will generally be able to obtain an image, but imaging stability does not guarantee that the results are
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Published 25 Sep 2014

Probing the electronic transport on the reconstructed Au/Ge(001) surface

  • Franciszek Krok,
  • Mark R. Kaspers,
  • Alexander M. Bernhart,
  • Marek Nikiel,
  • Benedykt R. Jany,
  • Paulina Indyka,
  • Mateusz Wojtaszek,
  • Rolf Möller and
  • Christian A. Bobisch

Beilstein J. Nanotechnol. 2014, 5, 1463–1471, doi:10.3762/bjnano.5.159

Graphical Abstract
  • current Itrans through the surface while the third tip measures the STM topography and the potential, simultaneously. Therefore, a feedback loop adjusts the dc tunnelling voltage such that the dc tunnelling current becomes zero. Thus, for each lateral tip position the applied dc tunnelling voltage
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Published 05 Sep 2014

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

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  • determined from slopes of lines in Figure 9. In these experiments, the normal contact force was varied in a controlled fashion by changing the feedback setpoint and recording corresponding changes in frictional (torsion) forces. Adhesion as determined from force–distance curves was negligible so the normal
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Published 10 Jul 2014

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

  • Lars Heepe,
  • Alexander E. Kovalev and
  • Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 903–909, doi:10.3762/bjnano.5.103

Graphical Abstract
  • reviewers for constructive feedback. This work was supported by German Science Foundation (DFG, No. GO 995/10-1 and Project No. C-10 within SFB 677) and the Ministry of Economic Affairs, Employment, Transport, and Technology, Schleswig-Holstein, Germany within the programme „Zukunft Meer“.
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Published 25 Jun 2014

Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

  • Xiaohong Wang,
  • Heinz C. Schröder and
  • Werner E. G. Müller

Beilstein J. Nanotechnol. 2014, 5, 610–621, doi:10.3762/bjnano.5.72

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  • that the stimulatory effect of bicarbonate ions on mineralization onto osteoblast-like SaOS-2 cells is strongly enhanced if the cells are exposed to polyP [64]. Finally, after hydrolysis of polyP through the alkaline phosphatase, the liberated orthophosphate inhibits in a negative feedback circle the
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Published 12 May 2014

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

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  • , the cornerholes, the molecules, and ‘off’ the molecules, with all the spectra having identical parameters. In order to eliminate artefacts in the subtraction due to the shift in height due to the topographic feedback, the 'on' spectra were first aligned (on the z axis) to the 'off' spectra by a least
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Published 01 Apr 2014

Control theory for scanning probe microscopy revisited

  • Julian Stirling

Beilstein J. Nanotechnol. 2014, 5, 337–345, doi:10.3762/bjnano.5.38

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  • Julian Stirling School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom 10.3762/bjnano.5.38 Abstract We derive a theoretical model for studying SPM feedback in the context of control theory. Previous models presented in the literature
  • that apply standard models for proportional-integral-derivative controllers predict a highly unstable feedback environment. This model uses features specific to the SPM implementation of the proportional-integral controller to give realistic feedback behaviour. As such the stability of SPM feedback for
  • a wide range of feedback gains can be understood. Further consideration of mechanical responses of the SPM system gives insight into the causes of exciting mechanical resonances of the scanner during feedback operation. Keywords: AFM; control theory; feedback; scanning probe microscopy
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Published 21 Mar 2014

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

Graphical Abstract
  • frequency and mode under consideration are externally excited [24]. In summary, FM and/or AM feedback systems can be employed in one [29], several [27] or all of the modes under consideration in order to quantify properties on the nanoscale through observables [30] while simultaneously enhancing sensitivity
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Published 11 Mar 2014

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

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  • certain limitations. AFM is used for both displacement and visualization of the initial and the final position of the NPs, but these two procedures cannot be performed simultaneously. Therefore there is no real-time visual feedback in a single line scan concerning the trajectory of the particle and its
  • ). During the manipulation, the tip moved parallel to the surface along a straight line without feedback loop. At the end of every manipulation event the tip was abruptly retracted from the NP to avoid sticking of the particle to the tip. Two different modes of the tip oscillation direction were used in
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Published 05 Feb 2014

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

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  • forces start to partially compensate the attractive forces), the non-monotonic behavior of the frequency shift as a function of the tip–sample distance makes a stable operation of the distance feedback loop impossible. Furthermore, a stable and inert tip is required to avoid that the tip deforms or picks
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Published 27 Jan 2014

Design criteria for stable Pt/C fuel cell catalysts

  • Josef C. Meier,
  • Carolina Galeano,
  • Ioannis Katsounaros,
  • Jonathon Witte,
  • Hans J. Bongard,
  • Angel A. Topalov,
  • Claudio Baldizzone,
  • Stefano Mezzavilla,
  • Ferdi Schüth and
  • Karl J. J. Mayrhofer

Beilstein J. Nanotechnol. 2014, 5, 44–67, doi:10.3762/bjnano.5.5

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  • , compensation for the resistance of the electrolyte by positive feedback has been applied to avoid errors when comparing catalysts with different platinum and carbon content [74]. A representative set of ORR measurements is provided for one of the catalysts studied (Pt@HGS 1–2 nm catalyst) in Figure 2A and
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Published 16 Jan 2014

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

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  • noise expressions equal to the theoretical value for self-oscillating circuits and in agreement with measurement, demonstrating that the PLL components neither modify nor contribute noise. Kelvin output noise is then investigated by modeling the surrounding bias feedback loop. A design rule is proposed
  • feedback loops of a nc-AFM as a function of the feedback controller settings, and showed that at a weak probe–surface interaction, the feedback loops can be considered independently whereas at a strong interaction, they become coupled. In our work on the dynamic behavior of AM-KFM [8], we studied the noise
  • designing operational amplifier circuits. The noise PSD is modeled as if the bandwidth was unlimited and later, the bandwidth is chosen as a function of the acceptable signal fluctuation. This approach is appropriate because (1) increasing the closed loop bandwidth of a stable feedback loop above a certain
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Published 02 Jan 2014

Structural development and energy dissipation in simulated silicon apices

  • Samuel Paul Jarvis,
  • Lev Kantorovich and
  • Philip Moriarty

Beilstein J. Nanotechnol. 2013, 4, 941–948, doi:10.3762/bjnano.4.106

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  • to modify the quality of the image. The process typically involves gentle indentations of the tip by 1–2 Å into the surface relative to the Δf feedback z position. As the tip is indented into the surface either material transfer, or atomic rearrangement can improve or worsen the quality of the AFM
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Published 20 Dec 2013

In situ growth optimization in focused electron-beam induced deposition

  • Paul M. Weirich,
  • Marcel Winhold,
  • Christian H. Schwalb and
  • Michael Huth

Beilstein J. Nanotechnol. 2013, 4, 919–926, doi:10.3762/bjnano.4.103

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  • changing the deposition parameters. Here, we present a first implementation of such a feedback control mechanism and employ an evolutionary genetic algorithm (GA) for the in situ optimization of the electrical conductivity of nanostructures that are prepared by FEBID [17]. By using the time gradient of the
  • adaption to every experimental circumstance with direct feedback promises a significant potential for future FEBID research. Furthermore, the application of the GA is not restricted to the optimization of conductance but can also be applied to, e.g., optimize dielectric properties of FEBID deposits by
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Published 17 Dec 2013

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

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  • is pushed into the material at a fixed load PI and an initial depth hI. The force is held constant by the system feedback throughout the creep time and the creep is detected as change in position required to compensate for the relaxation and to maintain constant force. Relaxation of the viscoelastic
  • for [84]. The bandwidth advantage has been extended to the MHz range, allowing an access to higher harmonics [85][86][87][88][89]. This provides several advantages: Higher harmonics can be exploited to separate the mechanical measurement from the topographic feedback, the signal-to-noise ratio can be
  • phase shift was removed by conducting a comparative measurement on a stiff, clean surface. By modifying the AFM setup, Hutter et al. induced small oscillations to the deflection signal by inserting the modulation directly to the feedback loop to generate a compensatory oscillation of the sample z-piezo
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Published 29 Nov 2013

Simulation of electron transport during electron-beam-induced deposition of nanostructures

  • Francesc Salvat-Pujol,
  • Harald O. Jeschke and
  • Roser Valentí

Beilstein J. Nanotechnol. 2013, 4, 781–792, doi:10.3762/bjnano.4.89

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  • the curves corresponding to the (thick) deposit and the substrate. Thus, under the assumption that the presence of a large number of electrons (slow or fast) enhances the dissociation rate of the precursor gas molecules adsorbed on the substrate, one can infer the following positive-feedback process
  • metal content, then the simulations show that a larger deposit density leads to enhanced electron backscattering. This implies that random fluctuations in deposit density could be amplified through positive feedback. The presented simulations therefore provide an overview of the effect of the primary
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Published 22 Nov 2013
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