Local work function on graphene nanoribbons

• Daniel Rothhardt,
• Amina Kimouche,
• Tillmann Klamroth and
• Regina Hoffmann-Vogel

Beilstein J. Nanotechnol. 2024, 15, 1125–1131, doi:10.3762/bjnano.15.91

• (f0 = 292 kHz, cL = 41 N/m) were used for imaging in the frequency modulation (FM) mode operated by a Nanonis electronic system. The tips were cleaned by sputtering (Ar pressure 5 × 10−3 Pa, energy 1 keV, 15 min) and annealing up to 375 K for 1–5 h (pressure below 1 × 10−7 Pa) prior to measurement

Signal generation in dynamic interferometric displacement detection

• Knarik Khachatryan,
• Simon Anter,
• Michael Reichling and
• Alexander von Schmidsfeld

Beilstein J. Nanotechnol. 2024, 15, 1070–1076, doi:10.3762/bjnano.15.87

• tip–surface forces, the cantilever displacement is [13]: where A is the cantilever oscillation amplitude and fexc is the excitation frequency kept at the resonance frequency of the cantilever for frequency-modulation NC-AFM. Further taking into account that the interferometer may be misaligned by the

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

• Mario Navarro-Rodriguez,
• Andres M. Somoza and
• Elisa Palacios-Lidon

Beilstein J. Nanotechnol. 2024, 15, 767–780, doi:10.3762/bjnano.15.64

• heterogeneous samples. This discrepancy arises from various sources depending on the operation mode and working parameters. In the frequency modulation mode (FM-AFM), a non-compensated bias voltage between tip and sample, from differences in the surface potential (SP), results in inaccurate height measurements

• maintain the system at resonance and track the frequency shift, a wide-bandwidth PLL (0.5–32 kHz) was enabled. In this operation mode, the amplitude signal carries information about dissipative interactions, as conservative forces only modify the resonant frequency. KPFM was operated in the frequency

• modulation mode (FM-KPFM) with an AC voltage of 700 mV at 7 kHz using platinum-coated silicon tips (Olympus AC240TM-R3, k = 2 N/m and f0 = 70 kHz). Using a dual lock-in amplifier (Zurich instruments, HF2LI), in addition to the KPFM channel, which provides information on the sample's SP, the 2ωelec

Design, fabrication, and characterization of kinetic-inductive force sensors for scanning probe applications

• August K. Roos,
• Ermes Scarano,
• Elisabet K. Arvidsson,
• Erik Holmgren and
• David B. Haviland

Beilstein J. Nanotechnol. 2024, 15, 242–255, doi:10.3762/bjnano.15.23

• amplitude modulation AFM (AM-AFM) and frequency modulation AFM (FM-AFM). Both modes, and their many variants, rely on lock-in detection of the motion signal, and in most cases, this signal is at the same frequency as the excitation. Cavity optomechanical detection principles can be used for both AM-AFM and

Dual-heterodyne Kelvin probe force microscopy

• Benjamin Grévin,
• Fatima Husainy,
• Dmitry Aldakov and
• Cyril Aumaître

Beilstein J. Nanotechnol. 2023, 14, 1068–1084, doi:10.3762/bjnano.14.88

• proportional to the dc potential difference, and one works (like in frequency-modulation KPFM) on a signal that is proportional to the electrostatic force gradient (through C''z). For that reason, this “side-band” KPFM is often referred to as a variant of FM-KPFM. Amplitude-modulated heterodyne KPFM [17

• is necessary because the first mode is used by the main AFM controller for topographic control (in frequency modulation mode in the case of non-contact AFM under UHV). In other words, it is the AFM controller which generates the source signal at ω0 + Δω0 which “excites” the mechanical oscillation of

Exploring internal structures and properties of terpolymer fibers via real-space characterizations

• Michael R. Roenbeck and
• Kenneth E. Strawhecker

Beilstein J. Nanotechnol. 2023, 14, 1004–1017, doi:10.3762/bjnano.14.83

• N/m (nominal), k = 12–21 N/m (measured)) were used for AFM scans. By simultaneously exciting the AFM cantilever to its first and second resonance (f1 = 160–190 kHz and f2 = 900–1150 kHz, Figure 1c) and applying two distinct control conditions (amplitude modulation (AM) and frequency modulation (FM

High–low Kelvin probe force spectroscopy for measuring the interface state density

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

Beilstein J. Nanotechnol. 2023, 14, 175–189, doi:10.3762/bjnano.14.18

• with respect to the cutoff frequency fc of carrier transport between the bulk and interface states and measuring the difference in CPD by KPFM. In high–low KPFM, frequency modulation (FM) KPFM (FM-KPFM) combined with FM-AFM is used to detect the tip–sample interaction force. FM-KPFM has several

From a free electron gas to confined states: A mixed island of PTCDA and copper phthalocyanine on Ag(111)

• Alfred J. Weymouth,
• Emily Roche and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2022, 13, 1572–1577, doi:10.3762/bjnano.13.131

• frequency of 879 Hz, and we used a modulation voltage amplitude of 20 mV after ensuring that spectra did not change in shape with modulation voltages between 5 and 20 mV. The bias voltage and AC signal were applied to the sample. AFM data were acquired in frequency-modulation mode [22] with a sensor

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

• sensitivity from operating on eigenmodes with the enhanced spatial resolution due to the electrostatic response being proportional to the second derivative of the capacitance gradient, C″ [57][76][83][84]. This enhanced sensitivity to short range forces (up to three times more sensitive than frequency

• modulation KPFM [53]) removes the influence of the cantilever and delivers enhanced bandwidth due to the high frequency of ωe [58]. Axt et al. found that Het-KPFM was the most accurate of all modes tested and was able to measure 99% of an applied potential difference even in the presence of strong stray

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

• KPFM. Moreover, AC-KPFM is applicable in both amplitude modulation and frequency modulation mode. Thus, it contributes to advancing SPV measurements in various environments, such as vacuum, air, and liquids. This method can be utilized for direct measurements of changes in surface potential induced by

• relatively slow SPV responses because it is based on the frequency modulation (FM) method in which bandwidth is limited to below a few kilohertz. Recently, a different type of methodology of directly measuring the SPV that is not based on a standard lock-in technique has been demonstrated and implemented to

• modulated signal, referring to the AC bias null method presented by Kohl and co-workers [28]. AC-KPFM avoids the problem of thermal drift and achieves a higher resolution. We provide the theory for both the amplitude modulation (AM) mode [29] and the frequency modulation (FM) mode [30] and demonstrate

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

• [47] operated in the frequency-modulation mode (resonance frequency f0 ≈ 25 kHz, spring constant k ≈ 1800 N/m, quality factor Q ≈ 14000, and oscillation amplitude A ≈ 0.5 Å). The tip mounted to the qPlus sensor consists of a 25 μm-thick PtIr wire, shortened and sharpened with a focused ion beam. A

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

• common feature is amplitude feedback. An alternative method uses the resonant frequency of the probe as a feedback parameter and is called frequency modulation AFM (FM-AFM). Selection of scan parameters in amplitude modulation AFM Let us consider which parameters we need to adjust in AM-AFM and what

• high-vacuum conditions, the AFM allows for obtaining atomic resolution [33]. Such measurements are usually carried out in the frequency modulation mode, which means that the driving frequency is automatically kept equal to the current resonant frequency of the probe, and the shift of the resonant

• using this mode for scanning were discussed in [3][4][5][35]. A comprehensive theoretical and experimental study of the approach curves was carried out in the framework of the development of the frequency modulation mode [12][13][14]. When approaching, the probe amplitude in the DM decreases only due to

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

• various contributions from the probe geometry and imaged features of the sample. In contrast to this, the currently implemented closed-loop (CL) variants of KPFM, either amplitude-modulation (AM) or frequency-modulation (FM), solely report on their final product in terms of the tip–sample contact

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

• frequency-modulation atomic force microscopy, the tip oscillates parallel to the surface. Existing amplitude calibration methods are not applicable for mechanically excited LFM sensors at low temperature. Moreover, a slight angular offset of the oscillation direction (tilt) has a significant influence on

• for a given amplitude and tilt. Finally, the amplitude and tilt are determined by fitting the simulation output to the data with oscillation. Keywords: frequency-modulation atomic force microscopy; lateral force microscopy; amplitude calibration; tilt estimation; Introduction Frequency-modulation

• 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

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

Direct observation of the Si(110)-(16×2) surface reconstruction by atomic force microscopy

• Tatsuya Yamamoto,
• Ryo Izumi,
• Kazushi Miki,
• Takahiro Yamasaki,
• Yasuhiro Sugawara and
• Yan Jun Li

Beilstein J. Nanotechnol. 2020, 11, 1750–1756, doi:10.3762/bjnano.11.157

• were performed using noncontact atomic force microscopy (NC-AFM) under ultrahigh vacuum (UHV) conditions, where the frequency modulation AFM (FM-AFM) method was used. The pressure was maintained below 3 × 10−11 Torr and the temperature was held at 78 K. As a probe, a commercially available Si

On the frequency dependence of viscoelastic material characterization with intermittent-contact dynamic atomic force microscopy: avoiding mischaracterization across large frequency ranges

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 1409–1418, doi:10.3762/bjnano.11.125

• (amplitude and phase in AM-AFM [2], and frequency and amplitude (or dissipation) in frequency-modulation AFM (FM-AFM [3]). Another very important consideration concerning the ability to explore the full range of viscoelastic types of behavior in the sample is the ability of the cantilever to indent it. As

Three-dimensional solvation structure of ethanol on carbonate minerals

• Hagen Söngen,
• Ygor Morais Jaques,
• Peter Spijker,
• Christoph Marutschke,
• Stefanie Klassen,
• Ilka Hermes,
• Ralf Bechstein,
• Lidija Zivanovic,
• John Tracey,
• Adam S. Foster and
• Angelika Kühnle

Beilstein J. Nanotechnol. 2020, 11, 891–898, doi:10.3762/bjnano.11.74

• nature. Experimental and Theoretical Methods Atomic force microscopy For the AFM experiments we used a modified commercial atomic force microscope [22] with custom photothermal cantilever excitation [23] and a custom three-dimensional scanning and data acquisition mode [24] in the frequency-modulation

Quantitative determination of the interaction potential between two surfaces using frequency-modulated atomic force microscopy

• Nicholas Chan,
• Carrie Lin,
• Tevis Jacobs,
• Robert W. Carpick and
• Philip Egberts

Beilstein J. Nanotechnol. 2020, 11, 729–739, doi:10.3762/bjnano.11.60

• geometries. In this manuscript, frequency modulation (FM) AFM was used to determine the interaction forces between two irregularly shaped solids: the apex of a silicon AFM probe with its native oxide and a slightly roughened, nominally flat single-crystal diamond surface. This substrate was chosen due to its

• contributes to the long-range interaction between tip and sample. Best-fit potential parameters were determined for the silicon oxide–diamond system and the spatial variance of these parameters was examined over different locations across the diamond sample. Experimental Frequency modulation atomic force

Atomic-resolution imaging of rutile TiO₂(110)-(1 × 2) reconstructed surface by non-contact atomic force microscopy

• Daiki Katsube,
• Shoki Ojima,
• Eiichi Inami and
• Masayuki Abe

Beilstein J. Nanotechnol. 2020, 11, 443–449, doi:10.3762/bjnano.11.35

• feedback control was applied in frequency-modulation mode [30] with constant amplitude oscillation. The cantilever deflection was detected using an optical interferometer [31]. Since the electrostatic force due to the contact potential difference (CPD) between the tip and sample prevents high-resolution NC

Implementation of data-cube pump–probe KPFM on organic solar cells

• Benjamin Grévin,
• Olivier Bardagot and
• Renaud Demadrille

Beilstein J. Nanotechnol. 2020, 11, 323–337, doi:10.3762/bjnano.11.24

• compensation potential (or surface potential (SP)) on the frequency modulation (fmod) of an illumination source. The first demonstration of light intensity-modulated KPFM (IM-KPFM) was carried out in 2008 by Takihara et al. on polycrystalline Si solar cells [12], and it has been recently applied to organic [13

• the chosen approach for pp-KPFM are finally discussed. pp-KPFM Implementation The experiments were performed on the basis of noncontact AFM (nc-AFM) under ultrahigh vacuum (UHV) with a beam deflection setup operated in frequency-modulation (FM) mode at room temperature. In the following, we only

• describe the general setup that has been used to implement data-cube pump–probe-KPFM (Figure 1b and Figure 1c). Additional technical information is provided in the experimental section. We kept the standard SPM controller configuration for frequency-modulation KPFM (FM-KPFM). Here, the electrostatic forces

Ion mobility and material transport on KBr in air as a function of the relative humidity

• Dominik J. Kirpal,
• Korbinian Pürckhauer,
• Alfred J. Weymouth and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2019, 10, 2084–2093, doi:10.3762/bjnano.10.203

• relationship between humidity, water coverage and movement speed, however, is complex. In this study we investigated the surface of KBr, a salt crystal, by using frequency-modulation atomic force microscopy (FM-AFM) using a qPlus sensor [9][10][11]. The aim of our experiments is a qualitative and quantitative

• per hour. The humidity was continuously measured and, if needed, adjusted during the measurement process. All AFM experiments were performed in the frequency-modulation mode with a qPlus sensor with a resonance frequency of 29 to 33 kHz and a stiffness of k = 1.8 kN/m. Typical image parameters were an

Kelvin probe force microscopy work function characterization of transition metal oxide crystals under ongoing reduction and oxidation

• Dominik Wrana,
• Karol Cieślik,
• Wojciech Belza,
• Christian Rodenbücher,
• Krzysztof Szot and
• Franciszek Krok

Beilstein J. Nanotechnol. 2019, 10, 1596–1607, doi:10.3762/bjnano.10.155

• [9] or Ti/TiOx/Ti memristive devices [10]. Of the two KPFM operation modes, frequency modulation (FM) has proven to be more suitable for the investigation of oxide nanostructures (due to the higher lateral resolution) as compared to amplitude modulation (AM) [11]. Therefore, in our study, we present

Nanoscale spatial mapping of mechanical properties through dynamic atomic force microscopy

• Zahra Abooalizadeh,
• Leszek Josef Sudak and
• Philip Egberts

Beilstein J. Nanotechnol. 2019, 10, 1332–1347, doi:10.3762/bjnano.10.132

• clarify the term “dissipative interaction” in this manuscript to be any energy loss through a viscoelastic pathway, where the same definition has been used in frequency modulation (FM) AFM studies, such as in [47], to explain energy loss through vertical elastic displacement of step edges. In this case

Imaging the surface potential at the steps on the rutile TiO₂(110) surface by Kelvin probe force microscopy

• Masato Miyazaki,
• Huan Fei Wen,
• Quanzhen Zhang,
• Yuuki Adachi,
• Jan Brndiar,
• Ivan Štich,
• Yan Jun Li and
• Yasuhiro Sugawara

Beilstein J. Nanotechnol. 2019, 10, 1228–1236, doi:10.3762/bjnano.10.122

• out with a custom-built ultrahigh-vacuum noncontact atomic force microscopy (NC-AFM) system operated at a temperature of 78 K with a base pressure below 4 × 10−11 mbar. The NC-AFM system was operated in the frequency-modulation mode [44] with a constant cantilever oscillation amplitude (5 Å). The

• , 2 min) because O2 affects the oxidation state and thus the electron density on the surface. KPFM measurements were carried out in the frequency-modulation mode [46]. An ac bias voltage (VAC) at the frequency fAC and a dc bias voltage (VDC) were applied to the sample. VDC was adjusted to compensate