Two dynamic modes to streamline challenging atomic force microscopy measurements

• Alexei G. Temiryazev,
• Andrey V. Krayev and
• Marina P. Temiryazeva

Beilstein J. Nanotechnol. 2021, 12, 1226–1236, doi:10.3762/bjnano.12.90

• ; Introduction More than 30 years have passed since the introduction of atomic force microscopy (AFM) [1]. This technique has established itself as an indispensable tool for characterization not only in physics and chemistry, but also in related fields of research including medicine, biology, and materials

• science The relative ease of use of AFM and a large number of operating modes allowed for the study of mechanical, magnetic, and electrical properties of various objects. At the same time, surface profile measurements remain both the main application of the method and the basis of two-pass technics of

• , in turn, limits the successful imaging of complex samples only to experienced researchers. In this article, we would like to draw the attention of AFM practitioners to two operating modes, the vertical mode [2] and the dissipation mode [3][4][5], which can greatly simplify and expand the

Open-loop amplitude-modulation Kelvin probe force microscopy operated in single-pass PeakForce tapping mode

• Gheorghe Stan and
• Pradeep Namboodiri

Beilstein J. Nanotechnol. 2021, 12, 1115–1126, doi:10.3762/bjnano.12.83

• (OL) variant of Kelvin probe force microscopy (KPFM) provides access to the voltage response of the electrostatic interaction between a conductive atomic force microscopy (AFM) probe and the investigated sample. The measured response can be analyzed a posteriori, modeled, and interpreted to include

• (PFT) mode. The topographical and electrical components were combined in a single pass by applying the electrical modulation only in between the PFT tip–sample contacts, when the AFM probe separates from the sample. In this way, any contact and tunneling discharges are avoided and, yet, the location of

• of the cantilever to the determined local contact potential difference between the AFM probe and the imaged sample. The removal of this unwanted contribution greatly improved the accuracy of the AM-KPFM measurements to the level of the FM-KPFM counterpart. Keywords: electrostatic interaction; Kelvin

A new method for obtaining model-free viscoelastic material properties from atomic force microscopy experiments using discrete integral transform techniques

• Berkin Uluutku,
• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 1063–1077, doi:10.3762/bjnano.12.79

• at the micro- and the nanoscale is commonly performed with the aid of force–distance relationships acquired using atomic force microscopy (AFM). The general strategy for existing methods is to fit the observed material behavior to specific viscoelastic models, such as generalized viscoelastic models

• correspondence. We illustrate the proposed technique on a model experiment involving a traditional ramp-shaped force–distance AFM curve, demonstrating good agreement between the viscoelastic characteristics extracted from the simulated experiment and the theoretical expectations. We also provide a path for

• unbounded inputs traditionally used to acquire force–distance relationships in AFM, such as ramp functions, in which the cantilever position is displaced linearly with time for a finite period of time. Keywords: atomic force microscopy; force spectroscopy; material properties; viscoelasticity

Revealing the formation mechanism and band gap tuning of Sb₂S₃ nanoparticles

• Maximilian Joschko,
• Franck Yvan Fotue Wafo,
• Christina Malsi,
• Danilo Kisić,
• Ivana Validžić and
• Christina Graf

Beilstein J. Nanotechnol. 2021, 12, 1021–1033, doi:10.3762/bjnano.12.76

• . Atomic force microscopy (AFM) as an additional method of size determination was applied to confirm the TEM results of the sample obtained after 30 s reaction time. AFM enables imaging of the nanoparticles under milder conditions than TEM and at ambient conditions so that thermal damage of the

• nanostructures due to the electron beam could be excluded [32]. The data of the AFM measurements are displayed in Figure 5. On the one hand, one can see single deflection peaks in Figure 5a, which are 1.5 nm and 2.3 nm in width (green and red marks). On the other hand, Figure 5b shows four deflection peaks

• precursor solution at 150 °C, the reaction mixture turned orange before it turned red about 30 s later but stayed clear. At this stage, type 0 seed particles of a size of 2–4 nm (diameter determined by AFM) were formed, which assembled into 20–40 nm-sized clusters. These particles were amorphous and did not

Molecular assemblies on surfaces: towards physical and electronic decoupling of organic molecules

• Sabine Maier and
• Meike Stöhr

Beilstein J. Nanotechnol. 2021, 12, 950–956, doi:10.3762/bjnano.12.71

• . To a lesser extent, metal oxides have also been used, for which defects and charging often pose additional challenges [44][45][46]. On electronically insulating surfaces, non-contact atomic force microscopy (AFM) is the method of choice to study molecular assemblies and individual molecules in real

• -dimensional AFM experiments. Although molecules adsorbed on bulk insulators are electronically decoupled, molecular self-assemblies can experience a substrate templating effect due to the presence of heterogeneous adsorption sites. Therefore, Söngen et al. [77] found on bulk calcite and magnesite that the

Self-assembly of Eucalyptus gunnii wax tubules and pure ß-diketone on HOPG and glass

• Miriam Anna Huth,
• Axel Huth and
• Kerstin Koch

Beilstein J. Nanotechnol. 2021, 12, 939–949, doi:10.3762/bjnano.12.70

• is unknown. In this study, extracted wax of E. gunnii leaves and pure ß-diketone were recrystallized on two different artificial materials and analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to study their formation process. Both the wax mixture and pure ß-diketone

• formed tubules similar to those on E. gunnii leaves. Deviating platelet-shaped and layered structures not found on leaves were also formed, especially on areas with high mass accumulation. High-resolution AFM images of recrystallized ß-diketone tubules are presented for the first time. The data showed

• formation of the tubules [26]. Atomic force microscopy (AFM) investigations further showed that the elongation of secondary alcohol tubules is based on a helical growth mechanism [27]. Recrystallization experiments with nonacosan-10-ol on non-biological substrates showed that the chemical and physical

Modification of a SERS-active Ag surface to promote adsorption of charged analytes: effect of Cu²⁺ ions

• Bahdan V. Ranishenka,
• Andrei Yu. Panarin,
• Irina A. Chelnokova,
• Sergei N. Terekhov,
• Peter Mojzes and
• Vadim V. Shmanai

Beilstein J. Nanotechnol. 2021, 12, 902–912, doi:10.3762/bjnano.12.67

• value below 10 nm. Taking into account the diameter of the NPs, we conclude that the major part of their surface would remain uncovered by the polymer layer in the plasmonic film on the SERS substrate. AFM images (Figure S3, Supporting Information File 1) confirm our conclusion. Topology map shows that

• microscopy (SEM) images were recorded using a Zeiss LEO SUPRA 25 (Germany). Transmitting electron microscopy (TEM) images were recorded using a Zeiss LEO 906E (Germany). SEM and TEM images were treated using ImageJ 1.51k freeware. AFM images were scanned in air using a BioScopeResolve (Bruker) atomic force

The role of convolutional neural networks in scanning probe microscopy: a review

• Ido Azuri,
• Irit Rosenhek-Goldian,
• Neta Regev-Rudzki,
• Georg Fantner and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2021, 12, 878–901, doi:10.3762/bjnano.12.66

• , convolutional neural networks, and how it is transforming the acquisition and analysis of scanning probe data. Keywords: atomic force microscopy (AFM); deep learning; machine learning; neural networks; scanning probe microscopy (SPM); Review Introduction: traditional machine learning vs deep learning Machine

• method was applied to low-resolution AFM images, resulting directly in higher resolution results [122]. The main obstacle to effective implementation of this method for AFM studies is the dissimilarity of different samples, making the choice of training sets critical. In this case, two sets, consisting

• of high-resolution AFM images, were used, that is “monomaterial” consisting of one ceramic sample, and “multimaterial” consisting of multiple samples of more complex nature (e.g., shell, bone, or nanoparticles). These were taken at various resolutions. The multimaterial set of images was six times

Reducing molecular simulation time for AFM images based on super-resolution methods

• Zhipeng Dou,
• Jianqiang Qian,
• Yingzi Li,
• Rui Lin,
• Jianhai Wang,
• Peng Cheng and
• Zeyu Xu

Beilstein J. Nanotechnol. 2021, 12, 775–785, doi:10.3762/bjnano.12.61

• Zhipeng Dou Jianqiang Qian Yingzi Li Rui Lin Jianhai Wang Peng Cheng Zeyu Xu School of Physics, Beihang University, Beijing 100083, China 10.3762/bjnano.12.61 Abstract Atomic force microscopy (AFM) has been an important tool for nanoscale imaging and characterization with atomic and subatomic

• resolution. Theoretical investigations are getting highly important for the interpretation of AFM images. Researchers have used molecular simulation to examine the AFM imaging mechanism. With a recent flurry of researches applying machine learning to AFM, AFM images obtained from molecular simulation have

• can be used to speed up the generation of training data and vary simulation resolution for AFM machine learning. Keywords: atomic force microscopy; Bayesian compressed sensing; convolutional neural network; molecular dynamics simulation; super resolution; Introduction Atomic force microscopy methods

9.1% efficient zinc oxide/silicon solar cells on a 50 μm thick Si absorber

• Rafal Pietruszka,
• Bartlomiej S. Witkowski,
• Monika Ozga,
• Katarzyna Gwozdz,
• Ewa Placzek-Popko and
• Marek Godlewski

Beilstein J. Nanotechnol. 2021, 12, 766–774, doi:10.3762/bjnano.12.60

• the tested PV cells, as measured with atomic force microscopy (AFM). The results for the photovoltaic cell modified with zinc oxide nanorods are shown in Figure 4a and Figure 4c. The results for the planar cell are shown in Figure 4b and Figure 4d. There are significant differences in the roughness

• (a, c) textured and (b, d) planar solar cells studied by SEM (top row) and AFM (bottom row). (a) External quantum efficiency and (b) current voltage characteristics of ZnO/Si solar cells. Current–voltage–temperature characteristics of (a) textured and (b) planar ZnO/Si solar cells. Temperature

Physical constraints lead to parallel evolution of micro- and nanostructures of animal adhesive pads: a review

• Thies H. Büscher and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2021, 12, 725–743, doi:10.3762/bjnano.12.57

• CC BY 4.0). (D–G) Atomic force microscopy (AFM) height images of the footprint droplets of the beetle Coccinella septempunctata (D,F) and the fly Calliphora vicina (E,G). (D) and (E) share the same colour scale. Brighter pixels correspond to higher z values. (F,G) Three-dimensional impressions of the

A review of defect engineering, ion implantation, and nanofabrication using the helium ion microscope

• Frances I. Allen

Beilstein J. Nanotechnol. 2021, 12, 633–664, doi:10.3762/bjnano.12.52

Impact of GaAs(100) surface preparation on EQE of AZO/Al₂O₃/p-GaAs photovoltaic structures

• Piotr Caban,
• Rafał Pietruszka,
• Jarosław Kaszewski,
• Monika Ożga,
• Bartłomiej S. Witkowski,
• Krzysztof Kopalko,
• Piotr Kuźmiuk,
• Katarzyna Gwóźdź,
• Ewa Płaczek-Popko,
• Krystyna Lawniczak-Jablonska and
• Marek Godlewski

Beilstein J. Nanotechnol. 2021, 12, 578–592, doi:10.3762/bjnano.12.48

• /interface needs to be properly prepared. In the experiments described here we examined eight different paths of GaAs surface treatment (cleaning, etching, passivation) which resulted in different external quantum efficiency (EQE) values of the tested photovoltaic (PV) cells. Atomic force microscopy (AFM

• performed with 2 kV Ar+ ions. Results and Discussion Examination of the devices by SEM and AFM Figure 3 and Figure 4 present AFM images of the surface of the devices (left side), top-view SEM images (right side), and SEM cross-section images (inset on the right) of the analyzed samples from the A series and

• B series, respectively. From the AFM results shown in Figure 3 and Figure 4, one can see that A1, A2, A4, B1, and B4 samples exhibit uniform surfaces by the means of polycrystalline thin film topography. By taking into consideration the roughness of the surfaces (RMS was measured for an area of 4

Local stiffness and work function variations of hexagonal boron nitride on Cu(111)

• Abhishek Grewal,
• Yuqi Wang,
• Matthias Münks,
• Klaus Kern and
• Markus Ternes

Beilstein J. Nanotechnol. 2021, 12, 559–565, doi:10.3762/bjnano.12.46

• non-contact atomic force microscopy (nc-AFM) to study h-BN on Cu(111). This template has interesting properties because the dielectric layer is only very weakly bound to the metal and shows an electronically induced Moiré superstructure [25][26]. First STM studies on this system pointed to only a

• buckling perpendicular to the surface. Interestingly, this is in contrast to measurements by Schwarz et al. who used a more local analysis of the corrugation by exploiting nc-AFM concluding an absolute height difference of 0.3–0.7 Å between “rim” and “valley” sites of the spatially corrugated monolayer [26

• ]. Results and Discussion STM/AFM on h-BN/Cu(111) As illustrated in Figure 1a, we employ nc-AFM to probe the electronic and topographic structure of a monolayer of h-BN on a Cu(111) surface. Figure 1b shows a typical large-scale constant-current STM scan of this structure. We observe the monolayer growing

Influence of electrospray deposition on C₆₀ molecular assemblies

• Antoine Hinaut,
• Sebastian Scherb,
• Sara Freund,
• Zhao Liu,
• Thilo Glatzel and
• Ernst Meyer

Beilstein J. Nanotechnol. 2021, 12, 552–558, doi:10.3762/bjnano.12.45

• method can yield single isolated molecules accompanied by surface modifications. Keywords: alkali halide; Au(111); bulk insulator; C60; electrospray; electrospray deposition; fullerene; high-vacuum electrospray deposition (HV-ESD); molecular assembly; nc-AFM; NiO; single molecule; thermal evaporation

• microscope (nc-AFM) working at room temperature to study formation and shape of C60 islands on three substrates with different intrinsic properties. These are, first, Au(111), a metal surface widely used in SPM studies, second, KBr(001), a bulk insulator allowing for the decoupling of molecular species and

• used as model surface in nc-AFM measurements [31][32][33][34], and, finally, NiO(001), a p-type wide-bandgap metal oxide with potential applications in photovoltaics [35][36][37]. For all cases, we show the typical C60 structures formed by TE and compare these with the results from HV-ESD. This allows

Determining amplitude and tilt of a lateral force microscopy sensor

• Oliver Gretz,
• Alfred J. Weymouth,
• Thomas Holzmann,
• Korbinian Pürckhauer and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2021, 12, 517–524, doi:10.3762/bjnano.12.42

• atomic force microscopy (AFM) is a non-contact atomic force microscopy technique where the frequency shift (Δf) of an oscillating tip is detected [1]. The frequency shift is a measure of the total force gradient acting on the tip, which includes both long-range and short-range contributions. A typical

• experimental setup is to study an isolated surface feature, for instance, a defect or an adsorbate, on a flat terrace. In case of “normal” AFM, where the tip oscillates perpendicular to the surface, long-range forces including electrostatic and van der Waals forces contribute to the measured Δf signal, which

• setup) or biaxial AFM with normal force detection is required. Experimentally, there are several methods for performing frequency-modulation lateral force microscopy, what we refer to as LFM in this manuscript. In 2002, Pfeiffer and co-workers excited a silicon cantilever in the first torsional mode [4

Boosting of photocatalytic hydrogen evolution via chlorine doping of polymeric carbon nitride

• Malgorzata Aleksandrzak,
• Michalina Kijaczko,
• Wojciech Kukulka,
• Daria Baranowska,
• Martyna Baca,
• Beata Zielinska and
• Ewa Mijowska

Beilstein J. Nanotechnol. 2021, 12, 473–484, doi:10.3762/bjnano.12.38

• , carbon, oxygen, and chlorine in Cl-PCN was performed and showed homogeneous distribution of all elements in the sample. As analyzed via atomic force microscopy (AFM, Figure 2a and Figure 2b) the as-prepared PCN aggregated as large sheets with thickness ranging from 1 to 4 nm (corresponding to 3–11 atomic

• packing motif of the tri-s-triazine units. The shift from 27.38° to 27.30° is caused by the increased internal distance of PCN by Cl doping, which is in good agreement with AFM data and suggests that Cl is located at the interlayers of carbon nitride. Moreover, the XRD and FTIR analyses confirmed that the

• energy-dispersive X-ray spectroscopy (EDX) elemental mappings of N, C, O, and Cl in Cl-PCN (f). AFM images and height profile of PCN (a, b) and Cl-PCN (c, d). (a) FTIR spectra and (b) XRD patterns of PCN and Cl-PCN. C 1s and N 1s XPS spectra of polymeric carbon nitride (a, b) and Cl-PCN (c, d). Structure

Reconstruction of a 2D layer of KBr on Ir(111) and electromechanical alteration by graphene

• Zhao Liu,
• Antoine Hinaut,
• Stefan Peeters,
• Sebastian Scherb,
• Ernst Meyer,
• Maria Clelia Righi and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2021, 12, 432–439, doi:10.3762/bjnano.12.35

• reduced by the decoupling effect of graphene, thus yielding different electrical and mechanical properties of the top KBr layer. Keywords: DFT; graphene; Ir(111); KBr; KPFM; nc-AFM; surface reconstruction; Introduction Many two-dimensional (2D) materials have excellent optical, mechanical

• with unconventional stoichiometries have been observed indirectly on graphene surfaces [37]. Here, we report on the formation of irregularly shaped KBr islands with corrugated stripe structures, observed on the (111) surface of Ir and analyzed by non-contact atomic force microscopy (nc-AFM) at room

• the iridium terraces. Figure 1a shows a large-scale topography image of a KBr island on Ir(111) measured by nc-AFM at room temperature. The monoatomic steps between the Ir terraces have a height of 235 pm as expected for Ir(111). The KBr islands are monolayers with an average height of 340 pm under

Exploring the fabrication and transfer mechanism of metallic nanostructures on carbon nanomembranes via focused electron beam induced processing

• Christian Preischl,
• Linh Hoang Le,
• Elif Bilgilisoy,
• Armin Gölzhäuser and
• Hubertus Marbach

Beilstein J. Nanotechnol. 2021, 12, 319–329, doi:10.3762/bjnano.12.26

• transfer process, AFM measurements were done before and after the transfer. In Figure 5a and Figure 5b, SEM and AFM images, respectively, of five different iron structures are depicted. One larger structure, which acts as a marker structure (the same one as in Figure 4a), and four 2 × 2 µm2 squares can be

• seen. The structures are distributed over an area of 50 × 40 µm2.The marker structure (7 × 5 µm2) is the largest transferred iron structure. In Figure 5c and Figure 5d SEM and AFM images, respectively, of the same five structures after the transfer onto a bulk SiO2 substrate are depicted. The large

• AFM experiments were performed with a JPK NanoWizard 4 by using non-contact mode. Cross-linking of SAMs into CNMs was achieved by using electron flood guns employing 100 eV electrons and an electron dose of 60 mC/cm2. Before starting the transfer process, the cross-linked CNMs were spin coated with a

Gold(I) N-heterocyclic carbene precursors for focused electron beam-induced deposition

• Cristiano Glessi,
• Aya Mahgoub,
• Cornelis W. Hagen and
• Mats Tilset

Beilstein J. Nanotechnol. 2021, 12, 257–269, doi:10.3762/bjnano.12.21

• and some volatile fragments. The technique has been employed in applications such as the fabrication of nanoconnectors [5], extreme ultra-violet lithography (EUVL) mask repair [6], AFM probe tips [7][8][9], nanodevices for plasmonics [10], gas sensors [11][12], optoelectronics [13], and magnetic [14

The nanomorphology of cell surfaces of adhered osteoblasts

• Christian Voelkner,
• Mirco Wendt,
• Regina Lange,
• Max Ulbrich,
• Martina Gruening,
• Susanne Staehlke,
• Barbara Nebe,
• Ingo Barke and
• Sylvia Speller

Beilstein J. Nanotechnol. 2021, 12, 242–256, doi:10.3762/bjnano.12.20

• signal is a force, pressure is applied to the sample. This is the case when using atomic force microscopy (AFM), giving rise to substantially depressed apparent heights on living and fixed cells [17]. Typically, mammalian cells exhibit Young's moduli in the range of 1 to 10 kPa while AFM probe pressures

• may correspond to ca. 10 MPa, assuming 1 nN loading force and 5 nm tip radius. Though the resulting artificial depression depths on the cellular membranes are about half a micrometer already at 1 nN, AFM is useful to measure the cortical actin network underneath the membrane [18]. Regarding the

• room temperature. Measurement principle and data preparation Scanning electron microscopy (SEM) was performed using a field-emission SEM (Gemini Supra 25, Zeiss) at 1 keV electron energy without Au coating. For SICM a commercial AFM/SICM setup (NX-bio, Park Systems, Korea) with a live-cell chamber (5

Mapping the local dielectric constant of a biological nanostructured system

• Wescley Walison Valeriano,
• Rodrigo Ribeiro Andrade,
• Juan Pablo Vasco,
• Angelo Malachias,
• Bernardo Ruegger Almeida Neves,
• Paulo Sergio Soares Guimarães and
• Wagner Nunes Rodrigues

Beilstein J. Nanotechnol. 2021, 12, 139–150, doi:10.3762/bjnano.12.11

• sample and the conductive substrate need to be present within the AFM image. This is a key condition since the conductive substrate establishes a reference level in the analysis. Having both in the imaged region guarantees that the cantilever amplitude and, consequently, the effective radius of the tip

• will be the same for different materials, which is critical for the applied capacitance model [29]. Also, having the conductive surface and the sample in the same AFM image guarantees the precision in the determination of the thickness of the sample. Wing sample preparation for SEM In order to study

• h is directly determined via AFM imaging. The microscope control software also determines the resonance frequency f0 and the elastic constant K of the cantilever using the thermal tune method [30][31]. A critical parameter is the tip–sample distance z, that consists of the height Hlift plus the

Correction: Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 137–138, doi:10.3762/bjnano.12.10

• microscopy (AFM); creep; force mapping; indentation; Kelvin–Voigt; static force spectroscopy (SFS); viscoelasticity; In the “Useful Viscoelastic Quantities” section of the original publication, it is stated that the storage modulus (E′) and storage compliance (J′) are inverses of one another (Equation 10

Fusion of purple membranes triggered by immobilization on carbon nanomembranes

• René Riedel,
• Natalie Frese,
• Fang Yang,
• Martin Wortmann,
• Raphael Dalpke,
• Daniel Rhinow,
• Norbert Hampp and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2021, 12, 93–101, doi:10.3762/bjnano.12.8

• histidine-tag at the extracellular side of a PM mutant (c-His PM). The functionalization and the resulting hybrid membrane were examined by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), confocal laser scanning microscopy (CLSM), and infrared

• Sphera electron analyzer with a resolution of 0.9 eV and an emission angle of 20°. AFM measurements were performed with a Bruker NanoScope® V system (Bruker Corporation, Billerica, MA, USA) in PeakForce mode using a PicoForce scanner for 50 × 50 µm2 topographical pictures. A Multimode 8 10364EVLR scanner

• samples were subsequently washed with 200 µL distilled water and dried in a nitrogen flow. For each sample the topography of a 50 × 50 µm2 area was investigated by AFM to evaluate substrate coverage. It has been shown that the WT PM patches do not form a continuous monolayer, but rather separately

Numerical analysis of vibration modes of a qPlus sensor with a long tip

• Kebei Chen,
• Zhenghui Liu,
• Yuchen Xie,
• Chunyu Zhang,
• Gengzhao Xu,
• Wentao Song and
• Ke Xu

Beilstein J. Nanotechnol. 2021, 12, 82–92, doi:10.3762/bjnano.12.7

• and fq in the in-phase mode (Figure 3 and Figure 6). We found a 0.05 mm tip has the best performance when the tip length is 0.65 mm in the anti-phase mode. However, Ax/Az in the anti-phase mode is 2.36, that is, φ is 23°. In frequency modulation-atomic force microscopy (FM-AFM), the frequency shift Δf

• than that of any tip with another diameter. Thus, 0.1 mm would be the best choice for the tip diameter. The last crucial factor to be considered is the Q factor. Lower Q factors will result in lower stability for both FM-AFM and amplitude modulation AFM (AM-AFM) [17]. As shown in Figure 9, the Q factor