Noncontact atomic force microscopy II
This is the second Thematic Series on noncontact atomic force microscopy (NC-AFM). It follows the first serieslaunched in 2012. Since its introduction two decades ago, NC-AFM has been used to image a large number of conducting, semi-conducting, and insulating material surfaces of technological and scientific importance with atomic resolution, thus contributing to nanoscale science in a major way with each passing year. The capabilities of NC-AFM are not only limited to atomic-resolution imaging: Force spectroscopy allows characterization of interatomic forces with unprecedented resolution in three spatial dimensions, while manipulation experiments at both low temperatures and room temperature have demonstrated the capability of the technique to controllably construct atomicscale structures on surfaces. This Thematic Series provides an overview of the current state-of-the-art in NC-AFM research, thereby delivering a snapshot of the newest trends in the field.
See also the Thematic Series:
Noncontact atomic force microscopy III
Noncontact atomic force microscopy
Advanced atomic force microscopy techniques IV
- Full Research Paper
- Published 20 Dec 2013
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Figure 1: The three tip structures considered, a structurally rigid ‘H3’ termination, and two dimer-terminate...
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Figure 2: Simulated F(z) curves for the (a) H3 and (b) D1 tip structures taken above the up (green and black ...
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Figure 3: Simulated F(z) curves for the D2 tip at rotations (a) 90°, (b) 180°, and (c) 270°. The energy dissi...
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Figure 4: Structural development during tip indentation. (a) Calculated F(z) approach and retraction curves f...
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Figure 5: Continued development of tip D2a via repeated tip indentations. (a) Calculated F(z) curve and (b) f...
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- Full Research Paper
- Published 02 Jan 2014
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Figure 1: An OpAmp circuit and its equivalent circuit of forward gain A and feedback gain F.
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Figure 2: PLL: in the blue box, the components belonging to the forward gain APLL, i.e., NCO, probe, optical ...
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Figure 3: Resonance frequency shift resulting from applying a voltage between a retracted tip and sample (bla...
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Figure 4: Phase detector output as function of modulation frequency (black squares), fitted with Equation 4, using fexc...
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Figure 5: Noise PSD at the photodetector output. Fiteed with Equation 9 (green) and decomposition into thermal excitati...
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Figure 6: Vector diagram showing the impact of amplitude noise on phase noise in the complex plain: main vect...
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Figure 7: Phase noise PSD at the lock-in phase detector output in open PLL loop and under probe excitation at ...
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Figure 8: Closed loop PLL response: measured (black squares) and computed (red line) according to Equation 16.
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Figure 9: Output noise PSD of the PLL in closed loop configuration: measured (black squares) and modeled acco...
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Figure 10: Kelvin loop and its equivalent circuit: the forward gain AK is the transfer function between Vpert ...
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Figure 11: Measurement of static forward gain of the open Kelvin loop.
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Figure 12: Schematic forward and reciprocal feedback response, for illustrating the choice of the Kelvin feedb...
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Figure 13: Measured (black squares) and calculated (red line) Kelvin closed loop gain of the setup of Figure 10.
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Figure 14: Measured (black squares) and computed (green line) Kelvin closed loop noise PSD of the setup of Figure 10. A...
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Figure 15: Design rule for cutoff and modulation frequencies in FM-KFM: gain of the PLL controller (continuous...
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Figure 16: Effective probed surface Seff depending on tip–sample separation z.
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Figure 17: Probe in the attractive part of the Van-der-Waals interaction.
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- Full Research Paper
- Published 27 Jan 2014
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Figure 1: (a) STM topography scan (V = 0.2 V, I = 0.3 nA) of PTCDA on Ag(111). The two molecule orientations ...
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Figure 2: Horizontal cut through the 3D field of the vertical tip–sample forces at a distance of z = 0.60 nm ...
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Figure 3: (a) Tip–sample forces as a function of z distance averaged for the area above the end groups and th...
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Figure 4: (a) Horizontal cut through the 3D force field at z = 0.60 nm and (b) vertical cuts at y = 0.9 nm an...
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Figure 5: Comparison of force versus distance curves for molecule sites A and B. The forces are averaged for ...
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- Full Research Paper
- Published 26 Feb 2014
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Figure 1: (a) Exemplary data from an experiment in which a single PTCDA molecule on the Au(111) surface was c...
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Figure 2: (a) Comparison between the ∂Fz/∂z(z) curves obtained from the initial ([11]) and the extended (this wor...
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Figure 3: One-dimensional spring model of the manipulation process. Left: The molecule is represented by a sp...
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Figure 4: (a) Comparison between the ∂Fz/∂z(z) curves of PTCDA lifted from Au(111), obtained for different ti...
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Supp. Info
- Full Research Paper
- Published 11 Mar 2014
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Figure 1: Phase shifts
![[Graphic 7]](/bjnano/content/inline/2190-4286-5-29-i27.png?max-width=637&scale=1.18182)
of higher harmonics, including the fundamental shift ![[Graphic 8]](/bjnano/content/inline/2190-4286-5-29-i28.png?max-width=637&scale=1.18182)
, when N = 10 external harmonic ...
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Figure 2: Phase shift analysis, in which the contrast in the higher harmonic phase shifts Δ
= abs((H2) − (H1)...
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Figure 3: Phase shift analysis, in which the contrast in the higher harmonic phase shifts Δ
= abs((H2) − (H1)...
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Figure 4: (a–c) Illustration of a cantilever oscillating above a surface and recovering the true height Δzc = ...
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- Full Research Paper
- Published 12 Mar 2014
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Figure 1: a) UAFM configuration with a mechanical vibration applied to the base of the cantilever and signal ...
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Figure 2: Amplitude ratio and phase of the a) first and b) second free eigenmodes of a cantilever vibrated in...
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Figure 3: Amplitude ratio and phase of the first eigenmode along the cantilever in a) the UAFM and c) AFAM co...
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Figure 4: Amplitude ratio and phase of the second eigenmode along the cantilever in a) the UAFM and c) AFAM c...
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Figure 5: Amplitude ratio, frequency shift, and phase of the first eigenmode versus contact stiffness in UAFM...
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Figure 6: Amplitude ratio, frequency shift, and phase of the first eigenmode versus contact stiffness in UAFM...
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Figure 7: a) Frequency shift, b) normalized amplitude, c) phase, and d) quality factor Q of the first eigenmo...
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Figure 8: a) Frequency shift, b) normalized amplitude, c) phase, and d) quality factor Q of the second eigenm...
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Figure 9: The frequency error introduced by a PLL in measuring the shift of the contact resonance frequency o...
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- Full Research Paper
- Published 13 Mar 2014
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Figure 1: Schematic representation of the KPFM setup and the MoS2 sample with the RIE SiO2.
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Figure 2: (a) Optical microscope image of an exfoliated MoS2 flake on a prepatterned (RIE) SiO2 substrate. A ...
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Figure 3: (a) NC-AFM image of MoS2 flake on SiO2 with a gold contact (height = 20 nm). Topography shows areas...
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Figure 4: (a) NC-AFM zoom-in of an area consisting of 1L, 2L and FL MoS2. (b) Corresponding KPFM image, calib...
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Figure 5: (a) NC-AFM topography of SLM on SiO2 and holes etched in SiO2 using RIE. (b) Work function map corr...
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- Full Research Paper
- Published 14 Mar 2014
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Figure 1: Example of measurement artifacts previously observed in single-mode AFM operation in liquids: disto...
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Figure 2: Bimodal AFM simulation illustrating the phase and amplitude relaxation of the second eigenmode: (a)...
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Figure 3: Illustration of eigenmode perturbation for two different cases. The results are color coded for the...
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Figure 4: Second eigenmode response for different second mode free amplitude values for the same conditions a...
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Figure 5: (a) Illustration of the drastically varying response of the higher eigenmode as the cantilever is b...
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Figure 6: Frequency space (a) and time space (b) responses of the system of Figure 5 for three different cantilever p...
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Figure 7: Typical eigenmode responses for bimodal and trimodal AFM operation in air with Q1 = 150, Q2 = 450, Q...
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Figure 8: Illustration of the force trajectory of five successive tip–sample impacts for bimodal AFM conditio...
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Figure 9: Illustration of the photodetector (PD) reading that would be obtained for a given second eigenmode ...
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Figure 10: Cantilever amplitude and phase response for various levels of damping in low-Q environments. The th...
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Figure 11: (a) Standard linear solid model; (b) illustration of tip–sample impact force trajectory and surface...
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- Full Research Paper
- Published 27 Mar 2014
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Figure 1: AFM images of xanthan scaffold A) in air, B) in isopropanol. C) Height histograms of xanthan scaffo...
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Figure 2: Typical force curves with different number of rupture events. A) Single event. B) Double events. C)...
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Figure 3: A) Schematic diagram of the superposition of force curves with single events. B) Distributions of r...
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Figure 4: A) Typical “type 1” (t1) force curve fitted with the WLC model. The inset is the model proposed to ...
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Figure 5: A,B) Typical single stretching event with one and two kinks (type 2), the insets are the proposed m...
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Figure 6: A) Typical double-peak force curve. B) “type 3” (t3) force curve. C,D) histograms of the difference...
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Figure 7: Mechanical responses composited by different type force curves. A) t1 + t2. B) t2 + t3. C) t1 + t3....
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- Full Research Paper
- Published 01 Apr 2014
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Figure 1: A) Constant Δf NC-AFM image of a C60 molecule adsorbed on the Si(111)-(7 × 7) surface showing atomi...
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Figure 2: Extracted short-range force curves from ‘on-minus-off’ extraction, and comparison to long-range fit...
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Figure 3: Close inspection of the divergence point between the ‘on’ and ‘off’ curves for A)–C) tip–C60 intera...
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- Full Research Paper
- Published 17 Apr 2014
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Figure 1: Synthesis of the wavelet retrieval method. (A) Schematic diagram of the modal shapes of the cantile...
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Figure 2: Dissipated energy per cycle vs time in each mode contributing to the dynamics described in Figure 3.
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Figure 3: 3D-representation of the main observables describing the tip dynamics during the jump-to-contact tr...
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Correction
- Full Research Paper
- Published 23 Apr 2014
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Figure 1: Determination of the geometric dimensions of a quarts tuning fork (Micro Crystal, type DS26 used fo...
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Figure 2: Photograph of the experimental setup. Not shown in the picture is the micrometer screw 1, which pus...
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Figure 3: Diagram of a “push” experiment to measure the stiffness of the free prong of a “qPlus” sensor by th...
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Figure 4: Image of the geometric model reflecting the geometry of an actual “qPlus” sensor. The model include...
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Figure 5: FEM simulation of von Mises stress. Analysis of the stress caused by the bending of the free prong....
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Figure 6: Diagram showing the results of the FEM simulation as a function of the shift of the origin. While f...
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Figure 7: Comparison between the beam formula, experimental measurements and FEM simulation with the force di...
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Figure 8: Comparison between tip on side (TOS) and tip on top (TOT) configurations as possible origin of the ...
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Figure 9: FEM simulation result displaying the influence of a tilted tungsten wire on the resulting spring co...
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Figure 10: Comparison of the spring constants from experiment with FEM simulations and calculations using the ...
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