Design of surface nanostructures for chirality sensing based on quartz crystal microbalance

• Yinglin Ma,
• Xiangyun Xiao and
• Qingmin Ji

Beilstein J. Nanotechnol. 2022, 13, 1201–1219, doi:10.3762/bjnano.13.100

• , Xu et al. studied real-time chiral recognition of CD films to isomers in the gas phase [69]. Based on atomic force microscopy (AFM) observations, functional β-CDs with a short sulfide group were inclined to form monolayers. In contrast, those with long sulfide groups produced a quasi-two-layer

A cantilever-based, ultrahigh-vacuum, low-temperature scanning probe instrument for multidimensional scanning force microscopy

• Hao Liu,
• Zuned Ahmed,
• Sasa Vranjkovic,
• Manfred Parschau,
• Andrada-Oana Mandru and
• Hans J. Hug

Beilstein J. Nanotechnol. 2022, 13, 1120–1140, doi:10.3762/bjnano.13.95

• Cantilever-based atomic force microscopy (AFM) performed under ambient conditions has become an important tool to characterize new material systems as well as devices. Current instruments permit robust scanning over large areas, atomic-scale lateral resolution, and the characterization of various sample

• properties using multifrequency and multimodal AFM operation modes. Research of new quantum materials and devices, however, often requires low temperatures and ultrahigh vacuum (UHV) conditions and, more specifically, AFM instrumentation providing atomic resolution. For this, AFM instrumentation based on a

• tuning fork force sensor became increasingly popular. In comparison to microfabricated cantilevers, the more macroscopic tuning forks, however, lack sensitivity, which limits the measurement bandwidth. Moreover, multimodal and multifrequency techniques, such as those available in cantilever-based AFM

Effects of focused electron beam irradiation parameters on direct nanostructure formation on Ag surfaces

• Jānis Sniķeris,
• Vjačeslavs Gerbreders,
• Andrejs Bulanovs and
• Ēriks Sļedevskis

Beilstein J. Nanotechnol. 2022, 13, 1004–1010, doi:10.3762/bjnano.13.87

• -contact atomic force microscopy (AFM) using the model Park NX10 AFM. The first experiment was conducted with beam current I as the variable parameter ranging from 7 to 500 pA. However, changing the value of I also changed the beam diameter d, which is a function of I and the working distance (WD). The

• the ones measured by AFM due to the tip convolution effect [37]; however, this should not affect the displayed trends. The results presented in Figure 3 show that the height of the nanostructures on the Ag surface could be increased by elevating the EB focus by a few microns above the surface during

• surface as functions of time following chamber decontamination by nitrogen plasma cleaning. Constant EB parameters are: U = 30 kV, I = 55 pA, d = 14 nm, t = 30 s, and α = 0°. A representative AFM image of a nanostructure on an Ag surface after sustaining damage from N plasma cleaning. Constant EB

Design of a biomimetic, small-scale artificial leaf surface for the study of environmental interactions

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

Beilstein J. Nanotechnol. 2022, 13, 944–957, doi:10.3762/bjnano.13.83

• secondary electron detector. The working distance was 4–7 mm. Atomic force microscopy analysis of recrystallized structures The thickness of the wax coating on glass (1400 µg) was examined with an atomic force microscope (AFM, NanoWizard II, JPK instruments, Berlin, Germany). For this purpose, the

• recrystallized wax layer on the glass was partially removed with a razor blade. The sample was then attached to a microscope slide with double-sided adhesive tape. The AFM recordings were performed in tapping mode (amplitude: 0.05 V; frequency: 302.9 kHz, line rate: 0.3 Hz, set point: 940 mV) with tapping

• scales between them. AFM analysis of recrystallized structures Like the SEM analysis, the AFM analysis showed granule-shaped structures on the artificial surface (1400 µg). By removing the wax with a razor blade, a distinct edge was created, showing a 1.12 ± 0.23 µm thick wax layer (Figure 5). Analysis

Comparing the performance of single and multifrequency Kelvin probe force microscopy techniques in air and water

• Jason I. Kilpatrick,
• Emrullah Kargin and
• Brian J. Rodriguez

Beilstein J. Nanotechnol. 2022, 13, 922–943, doi:10.3762/bjnano.13.82

• liquid environments whilst needing the smallest AC bias for operation. Keywords: AFM; atomic force microscopy; closed loop; Kelvin probe force microscope; KPFM; open loop; performance; signal-to-noise ratio; Introduction Atomic force microscopy (AFM) is an enabling technique for the nanoscale mapping

• forces in KPFM is generally expressed as the minimum detectable CPD [53], and is directly limited by the geometry of the interaction, thermal noise of the cantilever, and the detection noise limits of the AFM [36][54]. Cantilevers have a number of eigenmodes, ωn, where there is a mechanical enhancement

• -mode [14][48][49][50]. The most common application of KPFM in AFM is CL AM-KPFM on the fundamental eigenmode where a bias feedback loop is employed to cancel the electrostatic force and to extract VCPD [10][60][61]. This single-frequency technique can also be used under OL conditions without a feedback

Temperature and chemical effects on the interfacial energy between a Ga–In–Sn eutectic liquid alloy and nanoscopic asperities

• Yujin Han,
• Pierre-Marie Thebault,
• Corentin Audes,
• Xuelin Wang,
• Haiwoong Park,
• Jian-Zhong Jiang and
• Arnaud Caron

Beilstein J. Nanotechnol. 2022, 13, 817–827, doi:10.3762/bjnano.13.72

• increase of the interfacial energy as a function of the temperature, which can be explained by the reactivity between SiOx and Ga and the occurrence of chemical segregation at the liquid alloy surface. Keywords: atomic force microscopy (AFM); interfacial energy; liquid alloy; Introduction Recently, room

• atomic force microscopy (AFM) tips of different chemistries as a function of the temperature (T = 21–90 °C) by AFM force spectroscopy using an XE100 AFM equipped with a heating stage (manufactured by Park Instruments, Republic of Korea). We recorded force–distance curves with PtSi-coated Si cantilevers

• (PtSi-cont, manufactured from NanoSensors, Switzerland), SiOx cantilevers (Contsc, manufactured from NanoSensors, Switzerland), and Au-coated Si cantilevers (ContscAu, manufactured from NanoSensors, Switzerland). Before measurements, the sensitivity of the AFM photodiode was calibrated by recording a

Optimizing PMMA solutions to suppress contamination in the transfer of CVD graphene for batch production

• Chun-Da Liao,
• Andrea Capasso,
• Tiago Queirós,
• Telma Domingues,
• Fatima Cerqueira,
• Nicoleta Nicoara,
• Jérôme Borme,
• Paulo Freitas and
• Pedro Alpuim

Beilstein J. Nanotechnol. 2022, 13, 796–806, doi:10.3762/bjnano.13.70

• analyzer had a pass energy of 20 eV. Atomic force microscopy The surface topographies of graphene were investigated by a Bruker Dimension Icon atomic force microscope (AFM), using PPP-NCH (NanosensorsTM) cantilevers with a tip radius smaller than 20 nm, a force constant of 42 N/m, and 250 kHz resonance

• frequency. The AFM measurement was carried out in tapping mode. A 633 nm laser light aimed at the back side of the cantilever tip was reflected toward a position-sensitive photodetector, which provides feedback signals to piezoelectric scanners that maintain the cantilever tip at constant height (force

Efficient liquid exfoliation of KP₁₅ nanowires aided by Hansen's empirical theory

• Zhaoxuan Huang,
• Zhikang Jiang,
• Nan Tian,
• Disheng Yao,
• Fei Long,
• Yanhan Yang and
• Danmin Liu

Beilstein J. Nanotechnol. 2022, 13, 788–795, doi:10.3762/bjnano.13.69

• concentration, centrifugation was not used. Measurement equipment UV−visible spectrophotometry was performed by using a Shimadzu UV-3101PC system. Atomic force microscopy (AFM) tests were performed in a Multimode 8 system. The Raman tests were performed on a WITec alpha300 RA confocal Raman microscopy system

Gelatin nanoparticles with tunable mechanical properties: effect of crosslinking time and loading

• Agnes-Valencia Weiss,
• Daniel Schorr,
• Julia K. Metz,
• Metin Yildirim,
• Saeed Ahmad Khan and
• Marc Schneider

Beilstein J. Nanotechnol. 2022, 13, 778–787, doi:10.3762/bjnano.13.68

• for 0.5 h imaged under liquid conditions by AFM are shown in Figure 1. Incorporating lysozyme as a protein drug up to an initial loading of 3 mg per 20 mg gelatin resulted in particles with comparable size (242.67 ± 11.32 nm), size distribution (0.132 ± 0.04), and a negative zeta potential at neutral

• significant for all different crosslinking times. The absolut Young's modulus values are significantly lower than reported before [17]. This can be due to different reasons such as a batch to batch variance of gelatin as a natural product, a difference in the measurement speed during the AFM experiment and

• , Germany). Fluorescein isothiocyanate-dextran 70 kDa (FITC-dextran) was purchased from TdB (Upsala Sweden). Pall Minimate™ tangential flow filtration capsules 300 kDa were obtained from VWR International GmbH (Darmstadt, Germany). Silicon wafers used as substrates in AFM experiments were derived from Plano

Direct measurement of surface photovoltage by AC bias Kelvin probe force microscopy

• Masato Miyazaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2022, 13, 712–720, doi:10.3762/bjnano.13.63

• microscopy (AFM) [22]. KPFM measures the contact potential difference (CPD), which corresponds to the difference in work function between the tip and the sample, consecutively in darkness and under illumination, to determine the SPV values: SPV = CPDlight − CPDdark. In this method, the thermal drift between

• force This signal is measured with a lock-in amplifier and compensated by VAC control, yielding the SPV value. To improve the sensitivity, ωm is usually tuned to the second (first) resonance frequency of the cantilever, while the first (second) resonance frequency is assigned to the AFM measurement [29

• time [31]. To reach sufficient sensitivity, the value should typically be larger than 1 V. Experimental The experiments were performed by customized ultrahigh-vacuum (UHV) noncontact atomic force microscopy (NC-AFM, UNISOKU) at a temperature T of 78 K with a base pressure below 5 × 10−11 Torr. The NC

Reliable fabrication of transparent conducting films by cascade centrifugation and Langmuir–Blodgett deposition of electrochemically exfoliated graphene

• Teodora Vićentić,
• Stevan Andrić,
• Vladimir Rajić and
• Marko Spasenović

Beilstein J. Nanotechnol. 2022, 13, 666–674, doi:10.3762/bjnano.13.58

• wavelength of 660 nm and the number of graphene layers was calculated for each sample, taking into account an absorption of 2.3% for each layer of graphene, as in the work by Bonaccorso and co-workers [43]. Although atomic force microscopy (AFM) is often employed to characterize graphene films [2][12][14][44

• ], applying that method to films that consist of heterogeneous flakes, such as Langmuir–Blodgett-deposited films, is more difficult. Since the thickness varies from flake to flake, only an average film thickness over a certain area makes sense. The area over which average thickness can be measured with AFM is

• limited by the scan size, at a maximum of about 50 µm × 50 µm. The best method for measuring the average film thickness with AFM is to make scans that show the underlying substrate as well as the film itself and to make a histogram of measured heights, where a narrow peak related to the substrate and a

Quantitative dynamic force microscopy with inclined tip oscillation

• Philipp Rahe,
• Daniel Heile,
• Reinhard Olbrich and
• Michael Reichling

Beilstein J. Nanotechnol. 2022, 13, 610–619, doi:10.3762/bjnano.13.53

• Philipp Rahe Daniel Heile Reinhard Olbrich Michael Reichling Fachbereich Physik, Universität Osnabrück, Barbarastrasse 7, 49076 Osnabrück, Germany 10.3762/bjnano.13.53 Abstract In the mathematical description of dynamic atomic force microscopy (AFM), the relation between the tip–surface normal

• . Experimentally, however, the sampling path representing the tip oscillating trajectory is often inclined with respect to the surface normal and the data recording path. Here, we extend the mathematical description of dynamic AFM to include the case of an inclined sampling path. We find that the inclination of

• measuring a heterogeneous atomic surface. We propose to measure the AFM observables along a path parallel to the oscillation direction in order to reliably recover the force along this direction. Keywords: atomic force microscopy; cantilever; quantitative force measurement; sampling path; Introduction

Revealing local structural properties of an atomically thin MoSe₂ surface using optical microscopy

• Lin Pan,
• Peng Miao,
• Anke Horneber,
• Alfred J. Meixner,
• Pierre-Michel Adam and
• Dai Zhang

Beilstein J. Nanotechnol. 2022, 13, 572–581, doi:10.3762/bjnano.13.49

• the optical contrast, one can estimate that the thickness of the more transparent areas of the MoSe2 flake is smaller than that of other regions. To visualize the CuPc molecule distribution on the MoSe2 flake, atomic force microscopy (AFM) was used, and the results are shown in Figure 1b. The insets

• in Figure 1b are high-resolution AFM images of CuPc/MoSe2. The upper inset exhibits a step from the SiO2/Si substrate to the border of the MoSe2 flake, and the lower inset shows a distinct transition from the border to the center of the MoSe2 flake. The MoSe2 flake is fully covered by CuPc molecule

• pronounced correlation, which is exemplarily indicated by the dashed red circle in Figure 2a and Figure 2b. Figure 2c shows the AFM topographic image of the corresponding region of CuPc/MoSe2. The surface of the MoSe2 flake is covered by some nanoparticles marked by the dashed red circle, which were reported

Effects of substrate stiffness on the viscoelasticity and migration of prostate cancer cells examined by atomic force microscopy

• Xiaoqiong Tang,
• Yan Zhang,
• Jiangbing Mao,
• Yuhua Wang,
• Zhenghong Zhang,
• Zhengchao Wang and
• Hongqin Yang

Beilstein J. Nanotechnol. 2022, 13, 560–569, doi:10.3762/bjnano.13.47

• unclear how mechanical properties regulate the cellular response to the environmental matrix. In this study, atomic force microscopy (AFM) and laser confocal imaging were used to qualitatively evaluate the relationship between substrate stiffness and migration of prostate cancer (PCa) cells. Cells

• . Analysis of AFM force–distance curves indicated that the elasticity of the cells cultured on 35 kPa substrates increased while the viscosity decreased. Wound-healing experiments showed that PCa cells cultured on 35 kPa substrates have higher migration potential. These phenomena suggested that the

• functions have not been well appreciated [16]. In recent years, alterations in the physical properties of cells have been considered as a marker of malignant transformation of cancer cells [17][18][19]. Based on atomic force microscopy (AFM) measurements, our group found that the progression of prostate

Influence of thickness and morphology of MoS₂ on the performance of counter electrodes in dye-sensitized solar cells

• Lam Thuy Thi Mai,
• Hai Viet Le,
• Ngan Kim Thi Nguyen,
• Van La Tran Pham,
• Thu Anh Thi Nguyen,
• Nguyen Thanh Le Huynh and
• Hoang Thai Nguyen

Beilstein J. Nanotechnol. 2022, 13, 528–537, doi:10.3762/bjnano.13.44

• grids with a diameter of around 50 nm (see Figure 3e, insert). The roughness of the films was further studied by AFM. The film with the honeycomb-like structure showed the highest average roughness (Sa) and root mean square roughness (Sq) of 24.179 and 30.443 nm, respectively (see Supporting Information

• thank Professor Tzu-Chien Wei, Department of Chemical Engineering, National Tsing Hua University, Taiwan, for his great help on EIS, AFM and Raman measurements. Funding This research was fully funded by Tra Vinh University under grant contract number 140/HĐ.HĐKH-ĐHTV

Investigation of electron-induced cross-linking of self-assembled monolayers by scanning tunneling microscopy

• Patrick Stohmann,
• Sascha Koch,
• Yang Yang,
• Christopher David Kaiser,
• Julian Ehrens,
• Jürgen Schnack,
• Niklas Biere,
• Dario Anselmetti,
• Armin Gölzhäuser and
• Xianghui Zhang

Beilstein J. Nanotechnol. 2022, 13, 462–471, doi:10.3762/bjnano.13.39

• values determined by STM are smaller than the areal density of ≈7 × 1017 m−2 and the pore diameter of 0.7 ± 0.1 nm determined using AFM [36]. This is mainly due to different imaging mechanisms and different threshold definitions used for pore determination. Finally, the evolution of electron-induced

Relationship between corrosion and nanoscale friction on a metallic glass

• Haoran Ma and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2022, 13, 236–244, doi:10.3762/bjnano.13.18

• surface dissolution at the interface of the two layers. The findings contribute to the understanding of mechanical contacts with metallic glasses under corrosive conditions by exploring the interrelation of microscopic corrosion mechanisms and nanoscale friction. Keywords: atomic force microscopy (AFM

• polarization curves of ZrNiTi MGs in NaCl solution and phosphate buffer recorded in an electrochemical AFM cell. In NaCl solution, no passivity is observed during anodic polarization. The current density increases rapidly even at a low applied potential (approx. 0 V). In contrast, the ZrNiTi MG in phosphate

• be found in [21]. The lack of height contrast in Figure 3a is explained by penetration of the AFM tip into the soft outer layer surrounding the scan field. No height difference can be measured between the surrounding area, where the tip penetrates the outer layer, and the scan field, where the outer

Theranostic potential of self-luminescent branched polyethyleneimine-coated superparamagnetic iron oxide nanoparticles

• Rouhollah Khodadust,
• Ozlem Unal and
• Havva Yagci Acar

Beilstein J. Nanotechnol. 2022, 13, 82–95, doi:10.3762/bjnano.13.6

• over vacuum should be generated to obtain the spatial frequency distribution in the image. Then, a noise-filtering mask from the reduced FFT preserving only the crystalline contributions from the original image should be generated to produce the filtered nanoparticle image [35]. An AFM analysis

• performed at magnetic mode indicated particles of approx. 20 nm in size, which suggests a slight particle aggregation (Figure 1b). According to the literature, it is usually not uncommon to obtain different results using AFM and TEM analysis. However, due to a higher resolution and material-related

• , holds great potential for effective gene/drug delivery coupled with dual-mode imaging. a) TEM image of SPION@bPEI. b) AFM micrograph image of SPION@bPEI (magnetic mode). c) X-ray diffraction pattern of SPION@bPEI prepared via the in situ coating method. Since the presence of the polymer prevented the

Nanoscale friction and wear of a polymer coated with graphene

• Robin Vacher and
• Astrid S. de Wijn

Beilstein J. Nanotechnol. 2022, 13, 63–73, doi:10.3762/bjnano.13.4

• challenging problem due to the complex viscoelastic properties and structure. Using molecular dynamics simulations, we investigate how a graphene sheet on top of the semicrystalline polymer polyvinyl alcohol affects the friction and wear. Our setup is meant to resemble an AFM experiment with a silicon tip. We

• of depositing, indenting, and sliding on graphene. In the final section, we draw some conclusions. Simulation Setup We simulate a slab of polyvinyl alcohol (PVA) coated with a single layer of graphene and a counterbody representing an AFM tip consisting of silicon. The simulations were performed

• particles of the AFM tip. This leads to a fairly small total tip mass. While this is not entirely physical, such a low mass will help speed up the dynamics and damping of the tip and save computation time without compromising the results [32]. We simulate the system with a time step of 1 fs. Substrate

Effect of lubricants on the rotational transmission between solid-state gears

• Huang-Hsiang Lin,
• Jonathan Heinze,
• Alexander Croy,
• Rafael Gutiérrez and
• Gianaurelio Cuniberti

Beilstein J. Nanotechnol. 2022, 13, 54–62, doi:10.3762/bjnano.13.3

• situation becomes very different since a continuum description of the materials might not be sufficient. The development of the atomic force microscope (AFM) [19] and the scanning tunneling microscope (STM) [20][21] has allowed for visualization and manipulation of nanoscale gears [22]. Those gears can be

Topographic signatures and manipulations of Fe atoms, CO molecules and NaCl islands on superconducting Pb(111)

• Carl Drechsel,
• Philipp D’Astolfo,
• Jung-Ching Liu,
• Thilo Glatzel,
• Rémy Pawlak and
• Ernst Meyer

Beilstein J. Nanotechnol. 2022, 13, 1–9, doi:10.3762/bjnano.13.1

• microscopy (STM) and atomic force microscopy (AFM) are required to accurately disentangle structural and electronic properties of atomic or molecular structures on these superconducting platforms. STM/AFM generally allows for a controlled repositioning of adsorbates, both by lateral and vertical

• enable the development of functionalized tips, obtained by picking up a single molecule from a surface. This has been an important milestone for low-temperature STM/AFM techniques since the CO tip nowadays enables systematic high-resolution measurements of surfaces, molecules and atoms [33][34][35]. It

• is, however, astonishing that most recent advances in manipulation experiments or contrast enhancement with functionalized tips are hitherto at their infancy, when studying a superconducting surface by STM/AFM. Although the earliest proposal for observing MZMs suggested to reposition Fe adatoms one

Measurement of polarization effects in dual-phase ceria-based oxygen permeation membranes using Kelvin probe force microscopy

• Kerstin Neuhaus,
• Christina Schmidt,
• Liudmila Fischer,
• Wilhelm Albert Meulenberg,
• Ke Ran,
• Joachim Mayer and
• Stefan Baumann

Beilstein J. Nanotechnol. 2021, 12, 1380–1391, doi:10.3762/bjnano.12.102

• |ceria, ceria|electron conductor, and electron conductor|electron conductor). Kelvin probe force microscopy (KPFM) is an atomic force microscopy (AFM)-based measurement method that can measure the local surface potential (or Volta potential) of the sample [18][19]. The surface potential is a sensitive

• % FeCo2O4 (CSO-FC2O) as electron-conductive phase in order to, first, locally change the defect chemistry of the material and, then, study the relaxation to the original surface potential state during uptake/release of oxygen from/to the surrounding air. By using an AFM tip as an electron-conductive

• nanoscale electrode, a constant voltage pulse was applied to the sample in order to achieve a local polarization with distinctly changed redox state and defect concentrations. In a subsequent mapping experiment, the AFM tip was used as Kelvin probe to scan the locally changed surface potential distribution

Alteration of nanomechanical properties of pancreatic cancer cells through anticancer drug treatment revealed by atomic force microscopy

• Xiaoteng Liang,
• Shuai Liu,
• Xiuchao Wang,
• Dan Xia and
• Qiang Li

Beilstein J. Nanotechnol. 2021, 12, 1372–1379, doi:10.3762/bjnano.12.101

• from measuring the alteration of cellular mechanics, which provides a guide for the innovation and development of anticancer drugs [11]. Atomic force microscopy (AFM) has matured into a forceful nanoscale platform for imaging biological samples and quantifying biomechanical properties of living cells

• under (almost) physiological conditions in situ. It offers nanoscale force sensitivity, the ability to work in liquid phases, and requires no staining [12][13][14]. With the development of AFM, researchers have been able to conduct extensive research on biological issues through imaging the

• been elucidated. Such elucidation could hint to possible early ways of diagnosis and efficient drugs for controlling or even curing pancreatic cancer. Herein, nanostructure and Young's modulus of normal and PCCs were measured with AFM. The results illustrate that the Young's modulus of normal cells

Cantilever signature of tip detachment during contact resonance AFM

• Devin Kalafut,
• Ryan Wagner,
• Maria Jose Cadena,
• Anil Bajaj and
• Arvind Raman

Beilstein J. Nanotechnol. 2021, 12, 1286–1296, doi:10.3762/bjnano.12.96

• connect the qualitative and quantitative behavior to experimental features. Keywords: atomic force microscopy (AFM); contact resonance; nonlinear normal mode (NNM); tip–sample detachment; photothermal excitation; Introduction Contact resonance atomic force microscopy (CR-AFM) [1][2], piezoresponse force

• microscopy (PFM) [3], and electrochemical strain microscopy (ESM) [4] are atomic force microscopy (AFM) [5] methods where the probe tip is held in contact with the sample at a constant average force while a small superimposed vibrational response is monitored. CR-AFM can measure the viscoelastic properties

• of a sample [6] and observe subsurface features in some biological and electronics samples [7][8][9][10][11][12]. PFM can measure piezoelectric and ferroelectric properties of a sample [13][14][15][16]. ESM can measure the ion diffusion in battery materials [4][17][18][19]. These different AFM

Enhancement of the piezoelectric coefficient in PVDF-TrFe/CoFe₂O₄ nanocomposites through DC magnetic poling

• Marco Fortunato,
• Alessio Tamburrano,
• Maria Paola Bracciale,
• Maria Laura Santarelli and
• Maria Sabrina Sarto

Beilstein J. Nanotechnol. 2021, 12, 1262–1270, doi:10.3762/bjnano.12.93

• through PFM [1][5][27] using a commercial Bruker-Veeco Dimension Icon AFM with a Co/Cr-coated-tip silicon cantilever (MESP-RC-V2, Bruker). Following the procedure described in [2][3], we scanned three different areas, 5 × 5 μm2 in size, of each sample, with 256 × 256 acquisition points per scanning area