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

A review on slip boundary conditions at the nanoscale: recent development and applications

• Ruifei Wang,
• Jin Chai,
• Bobo Luo,
• Xiong Liu,
• Jianting Zhang,
• Min Wu,
• Mingdan Wei and
• Zhuanyue Ma

Beilstein J. Nanotechnol. 2021, 12, 1237–1251, doi:10.3762/bjnano.12.91

• nanoscale systems [8][34][38][39]. For example, based on surface force apparatus (SFA) and atomic force microscopy (AFM) measurements, many researchers have investigated the slippage characteristics of nanoconfined liquid flows and derived the slip length according to its correlation with the hydrodynamic

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