Protruding hydrogen atoms as markers for the molecular orientation of a metallocene

• Linda Laflör,
• Michael Reichling and
• Philipp Rahe

Beilstein J. Nanotechnol. 2020, 11, 1432–1438, doi:10.3762/bjnano.11.127

• atoms were used as probe particles and frequency-shift Δf data were calculated for an oscillation amplitude of 0.5 nm. Lateral and vertical stiffness were chosen as 0.5 and 20 N/m, respectively. FDCA molecular models in the DFT-optimised geometries (using geo 1 and geo 2 from [22], see Figure 1a,b) were

• frequency-shift images were acquired at different tip–sample distances, see Figure 2b–e. Data were acquired above a region where several FDCA molecules were arranged along the direction (see STM data in Figure 2a), with a molecular separation determined by the CaF2(111) lattice periodicity of 669 pm. Upon

• Figure 3b for geo 2. Conclusion We have investigated the origin of the dumbbell shape, which is observed when imaging FDCA molecules on CaF2(111) surfaces with NC-AFM. Based on a comparison of experimental constant-height frequency-shift data with image calculations using the probe particle model, we

Atomic defect classification of the H–Si(100) surface through multi-mode scanning probe microscopy

• Jeremiah Croshaw,
• Thomas Dienel,
• Taleana Huff and
• Robert Wolkow

Beilstein J. Nanotechnol. 2020, 11, 1346–1360, doi:10.3762/bjnano.11.119

• -functionalized tips. A true measurement of the force interaction between the tip and sample can be visualized with frequency-shift maps generated by non-contact AFM [28]. In our work, we observe two different imaging modes that we denote as dark (Figure 1g) and bright contrast AFM (Figure 1h), based on the

• , where the height-dependent frequency shift spectra (Δf(z)) taken above select positions on the surface (see Figure 1g,h for positions), shows significantly different character for each tip termination. To highlight the termination-dependent reactivity, frequency shift difference spectra [42] were

• artificially saturated from a 2.4 nA range to better show the H–Si atoms of the surface relative to the DB. A full-scale image of the DB is shown in Supporting Information File 1, Figure S8. Finally, AFM analysis in Figure 2a-5 and Figure 2a-6 presents the DB as a large negative frequency shift, with both tip

Measurement of electrostatic tip–sample interactions by time-domain Kelvin probe force microscopy

• Christian Ritz,
• Tino Wagner and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2020, 11, 911–921, doi:10.3762/bjnano.11.76

• an alternative approach to find the surface potential without lock-in detection. Our method operates directly on the frequency-shift signal measured in frequency-modulated atomic force microscopy and continuously estimates the electrostatic influence due to the applied voltage modulation. This

• results in a continuous measurement of the local surface potential, the capacitance gradient, and the frequency shift induced by surface topography. In contrast to conventional techniques, the detection of the topography-induced frequency shift enables the compensation of all electrostatic influences

• . Another possibility for compensating the remaining frequency shift is the use of two-pass methods with feed-forward compensation techniques [20][21]. In this paper, we present a time-domain (TD) controller for KFM as a single-pass solution to the problem outlined above. Our method uses a Kalman filter 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 of our findings. Results and Discussion AFM results A vertical slice of the frequency shift (Δνexc) obtained at the calcite (10.4)–ethanol interface is shown in Figure 1a. The average over all data shown in the slice is given as a vertical profile (i.e., as function of the z-piezo displacement zp

• ) in Figure 1b. The corresponding data for the magnesite-ethanol interface is shown in a similar fashion in the second row of Figure 1 (panels c and d). In both cases, the frequency shift exhibits local minima and maxima. Close to the surface (at the bottom), laterally alternating local maxima with a

• approximation” [19][20]. We note that it is relevant to discuss whether this approximation holds true for ethanol as well. However, in this work, we assume that a single ethanol molecule probes the solvation structure. In this model, the frequency shift modulation is approximately proportional to the solvent

Light–matter interactions in two-dimensional layered WSe₂ for gauging evolution of phonon dynamics

• Avra S. Bandyopadhyay,
• Chandan Biswas and
• Anupama B. Kaul

Beilstein J. Nanotechnol. 2020, 11, 782–797, doi:10.3762/bjnano.11.63

• frequency shift, ΔωT of the and A1g Raman active modes for 1L WSe2 with increasing T. The results were fit linearly using Equation 7 from which the slope χT was computed to be about −0.0145 cm−1/K and −0.0168 cm−1/K for the and A1g modes, respectively. The nonlinear perturbation of Raman shift for the

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

• topography, among other parameters. In order to determine the interaction force behavior as a function of the separation distance, we measured the frequency shift of the oscillating cantilever as a function of the separation distance (Δf–d curves) between a silicon AFM probe and a diamond sample. An

• analytical relationship between the resonance frequency shift and the tip–sample interaction force in FM-AFM was first derived by Giessibl [42] and is seen in the following equation: In Equation 1, Δf represents the change in the primary flexural resonance frequency of the cantilever near the surface, fres

• topographic imaging of the surface, the tip–sample contact potential difference was determined by measuring the probe frequency shift as a function of the sample bias voltage. A DC bias was then applied to the sample surface for all subsequent measurements to compensate for this potential difference. Initial

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

• are detected by demodulating the modulated component (ωmod) of the frequency-shift signal (Δf) with the LIA. The reference bias modulation voltage (Vmod, ωmod) and the compensation voltage generated by the KPFM feedback loop (VKPFM) are internally summed by the SPM unit. To generate the modulated bias

• = −CPD [39]. The KPFM data are presented as Vdc images also referred to as KPFM potential or SP images for simplicity. A lock-in amplifier (Signal Recovery 7280) was used to measure simultaneously the modulation of the frequency shift at the electrostatic excitation frequency. The ‘in-phase’ amplitude of

• feeding the frequency-shift signal (Δf) from the SPM phase-lock loop to the LIA input (KPFM operated in frequency-modulation mode). Using the SPM unit (block 1), the reference bias modulation voltage (Vmod, ωmod) is added to the compensation voltage generated by the KPFM feedback loop. The sum is

Nitrogen-vacancy centers in diamond for nanoscale magnetic resonance imaging applications

• Alberto Boretti,
• Lorenzo Rosa,
• Jonathan Blackledge and
• Stefania Castelletto

Beilstein J. Nanotechnol. 2019, 10, 2128–2151, doi:10.3762/bjnano.10.207

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

• amplitude A = 500 pm and a frequency-shift set point of Δf = +10 to +25 Hz. Data and image processing was performed with MATLAB (The MathWorks, Inc.) and WSxM [28]. Results and Discussion Initial experiments with poking holes This experiment shall investigate qualitatively how the material transport rate

Subsurface imaging of flexible circuits via contact resonance atomic force microscopy

• Wenting Wang,
• Chengfu Ma,
• Yuhang Chen,
• Lei Zheng,
• Huarong Liu and
• Jiaru Chu

Beilstein J. Nanotechnol. 2019, 10, 1636–1647, doi:10.3762/bjnano.10.159

• embedded metal layer leads to an obvious CR-AFM frequency shift and therefore its unambiguous differentiation from the polymer matrix. The contact stiffness contrast, determined from the tracked frequency images, was employed for quantitative evaluation. The influence of various parameter settings and

• structures. In Figure 2c, we show the histogram of the resonance frequency image (Figure 2b), which demonstrates two peaks at 275.60 ± 0.10 and 275.92 ± 0.08 kHz. They correspond to the measured resonance frequency on the polymer matrix and above the embedded Au layer, respectively. The resonance frequency

• shift can be unambiguously distinguished. The contact stiffnesses were evaluated to be 151.4 ± 0.5 N/m above the circuit and 149.6 ± 0.5 N/m on the polymer substrate, resulting in a contrast metric of 1.20 ± 0.67% according to Equation 12. Influence of experimental parameters In order to optimize the

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

• /AFM system, where KPFM, LC-AFM and STM measurements were performed. KPFM, operating in FM mode, was used with a single-pass method, with three feedback loops maintaining the oscillation amplitude, phase and frequency shift [56]. The real oscillation amplitude was in the range of 10 nm. In order to

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

• given offset, z + offset, using KPFM to measure the CPD. The given offset (100 pm) was applied to avoid the influence of a phantom force [48][49] or induced dipole moments [50]. Force spectroscopy measurements [51] were performed by recording the frequency shift (Δf) as a function of the tip–sample

Direct growth of few-layer graphene on AlN-based resonators for high-sensitivity gravimetric biosensors

• Jimena Olivares,
• Teona Mirea,
• Lorena Gordillo-Dagallier,
• Bruno Marco,
• José Miguel Escolano,
• Marta Clement and
• Enrique Iborra

Beilstein J. Nanotechnol. 2019, 10, 975–984, doi:10.3762/bjnano.10.98

• frequency shift due to the covalent binding of streptavidin to the EDC on the device surface. Then BSA 0.1% in weight in PBS was used as blocking agent and, finally, the surface was exposed to biotinylated anti-IgG antibodies by circulating a 330 nM solution in the system. It is worth mentioning that during

• -streptavidin bound surface. After washing with PBS, the biotinylated anti-IgG antibody 330 nm was fed to the system. In this step the frequency shift of 110 kHz indicates the binding of anti-IgG to the surface. This frequency shift is slightly higher than for the covalent functionalization case although such

Comparing a porphyrin- and a coumarin-based dye adsorbed on NiO(001)

• Sara Freund,
• Antoine Hinaut,
• Nathalie Marinakis,
• Edwin C. Constable,
• Ernst Meyer,
• Catherine E. Housecroft and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2019, 10, 874–881, doi:10.3762/bjnano.10.88

• study and do not influence the reported results. Figure 2b shows the frequency-shift signal acquired using the multipass imaging technique [14][15][35][36] clearly showing atomic resolution of the NiO(001) surface. Employing this method, the crystallographic directions of the substrate are resolved with

• ). (b) Frequency-shift (Δf1) signal of the same surface at atomic resolution, recorded in the second line scan of the multipass technique with following scan parameters: = 4 nm, Δf1 = −42 Hz) and zoffset = −700 pm. (a) Large-scale topographic image showing that Cu-TCPP molecules form islands on the

Review of time-resolved non-contact electrostatic force microscopy techniques with applications to ionic transport measurements

• Aaron Mascaro,
• Yoichi Miyahara,
• Tyler Enright,
• Omur E. Dagdeviren and
• Peter Grütter

Beilstein J. Nanotechnol. 2019, 10, 617–633, doi:10.3762/bjnano.10.62

• build-up in the sample at the location of the AFM tip if an appropriate voltage is applied across the tip–sample gap. Measuring the resonance frequency shift as a function of time after the light is turned on/off then allows for the charging/discharging time to be directly acquired, revealing

• information about charge generation and transport in the sample. This was first performed by Krauss et al. who observed charging of photoexcited CdSe nanocrystals by direct frequency shift measurements after illumination [26]. The concept outlined above can be applied to measure ionic transport in ionic

• directly calculated from the fit results. Note that since the frequency shift is quadratic in voltage and it is the voltage being changed here, we must first take the square root of the data before fitting. The results are shown in Figure 2b where the shaded area is the region for which τ* < τPLL ≈ 600 μs

Nitrous oxide as an effective AFM tip functionalization: a comparative study

• Taras Chutora,
• Bruno de la Torre,
• Pingo Mutombo,
• Jack Hellerstedt,
• Jaromír Kopeček,
• Pavel Jelínek and
• Martin Švec

Beilstein J. Nanotechnol. 2019, 10, 315–321, doi:10.3762/bjnano.10.30

• with FePc, we performed site-specific frequency-shift spectroscopy Δf(z) measurements on the outer C–C bonds and centers of the peripheral benzene molecules indicated by the red and green dots in Figure 5a. In Figure 5b, the short-range Δf curves recorded with N2O and CO tips are shown (after

Raman study of flash-lamp annealed aqueous Cu₂ZnSnS₄ nanocrystals

• Yevhenii Havryliuk,
• Oleksandr Selyshchev,
• Mykhailo Valakh,
• Alexandra Raevskaya,
• Oleksandr Stroyuk,
• Constance Schmidt,
• Volodymyr Dzhagan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2019, 10, 222–227, doi:10.3762/bjnano.10.20

• likely related to minor organic byproducts of the CZTS NCs synthesis reaction, was absent, allowing for the recording of the high-quality Raman spectra. However, the position of the main peak was observed at about 5 cm−1 lower frequency (Figure 1). There are two possible reasons of the observed frequency

• shift in the films (as well as for the solutions stored for longer times): (i) rearrangement of cations, possibly stimulated by a reaction with oxygen and accompanied by a change of the charge state of Cu from +1 to +2; or (ii) re-crystallization of the NCs into larger NCs while preserving the crystal

Electrostatic force microscopy for the accurate characterization of interphases in nanocomposites

• Diana El Khoury,
• Richard Arinero,
• Jean-Charles Laurentie,
• Mikhaël Bechelany,
• Michel Ramonda and
• Jérôme Castellon

Beilstein J. Nanotechnol. 2018, 9, 2999–3012, doi:10.3762/bjnano.9.279

• tip was retracted from the surface at a known distance, called the lift distance. At this stage, the component of the frequency shift that varies at the double frequency of the applied electrical voltage was extracted because it represents the purely capacitive response of the material. Finally, the

• sample dimensions and permittivity values should be relatively small, the statistical analysis was performed using EFM measurements acquired on 12 × 3 µm2 images based on an average of 30 particles [37]. The calculated average topography and electrical frequency shift (2ω − Δf0) profiles for PS + 100 nm

• component of the electrostatic force was studied, like in previous finite-element EFM models [64]. In our simulations, the purely capacitive DC signal (perfect insulators) was computed (Figure 11). Then, to correlate AC measurements with the simulations, the amplitude of the demodulated 2ω-frequency shift

In situ characterization of nanoscale contaminations adsorbed in air using atomic force microscopy

• Jesús S. Lacasa,
• Lisa Almonte and
• Jaime Colchero

Beilstein J. Nanotechnol. 2018, 9, 2925–2935, doi:10.3762/bjnano.9.271

• ) = πε0R/d2. Then, the total frequency-shift induced by the tip–sample interaction is: where the first term containing the Hamaker constant A describes the van der Waals interaction and the second term describes the electrostatic interaction. We note that the chemical composition of the sample will

• thus of type “uncleaned-new”, which is “almost clean”, as discussed below in more detail. Figure 2 shows the topography (a), the error signal of the feedback (frequency shift, (b)), the electrostatic capacity signal (EAFM2ν, see Experimental section, (c)) as well as the contact potential (e), which are

• ). Platinum-coated silicon tips (ν0 ≈ 70 kHz) with a nominal force constant of 3 N/m were used. The nominal radius value for tip apex of these probes is specified as 15 nm by the manufacturer. As described in [50][51] electrostatic measurements were performed by detecting the frequency shift (and thus the

Size-selected Fe₃O₄–Au hybrid nanoparticles for improved magnetism-based theranostics

• Maria V. Efremova,
• Yulia A. Nalench,
• Eirini Myrovali,
• Anastasiia S. Garanina,
• Ivan S. Grebennikov,
• Polina K. Gifer,
• Maxim A. Abakumov,
• Marina Spasova,
• Makis Angelakeris,
• Alexander G. Savchenko,
• Michael Farle,
• Natalia L. Klyachko,
• Alexander G. Majouga and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2018, 9, 2684–2699, doi:10.3762/bjnano.9.251

• out-of-phase. At this point, r2 increases with the NP size. This regime is called the motional average regime (MAR). Therefore, MAR is predicted for relatively small iron oxide NPs, where water diffusion near NPs occurs on much faster timescales than the resonance frequency shift, resulting in

Nanoantenna structures for the detection of phonons in nanocrystals

• Alexander G. Milekhin,
• Sergei A. Kuznetsov,
• Ilya A. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Alexander V. Latyshev,
• Volodymyr M. Dzhagan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2018, 9, 2646–2656, doi:10.3762/bjnano.9.246

• NC monolayers, their intensity increase entails a high frequency shift of the LSPR minima, which is more pronounced for H-shaped nanoantennas (Figure 8c and 8d). This shift occurs due to the change in dielectric function of the medium surrounding the nanoantennas. At a relatively thick CdSe NC

Effective sensor properties and sensitivity considerations of a dynamic co-resonantly coupled cantilever sensor

• Julia Körner

Beilstein J. Nanotechnol. 2018, 9, 2546–2560, doi:10.3762/bjnano.9.237

• which becomes possible with the derived analytic expressions. Besides the description of effective sensor properties, it was studied how the thermal noise and, consequently, minimal detectable frequency shift for the co-resonantly coupled sensor represented by a coupled harmonic oscillator could be

• derived. Due to the complex nature of the coupled system’s transfer function and the required analysis, it is beyond the scope of this publication to present a full solution. Instead, a simplified approach to estimate the minimal detectable frequency shift for the co-resonant system based on the effective

• resonance frequency ω0 is measured and, hence, the sensitivity of a cantilever sensor can be defined as the obtainable frequency shift with respect to an external interaction. This interaction can either be a force gradient represented by Δk or a mass change Δm (either point mass at the beam’s end or

Dumbbell gold nanoparticle dimer antennas with advanced optical properties

• Janning F. Herrmann and
• Christiane Höppener

Beilstein J. Nanotechnol. 2018, 9, 2188–2197, doi:10.3762/bjnano.9.205

• maintained with sub-nanometer accuracy to 2–4 nm by means of a force feedback loop regulating on the frequency shift of the force sensor, which is excited at its resonance frequency. The fluorescence emission rate as a function of the antenna–sample distance is recorded with the feedback loop switched off

Electrospun one-dimensional nanostructures: a new horizon for gas sensing materials

• Muhammad Imran,
• Nunzio Motta and
• Mahnaz Shafiei

Beilstein J. Nanotechnol. 2018, 9, 2128–2170, doi:10.3762/bjnano.9.202

A scanning probe microscopy study of nanostructured TiO₂/poly(3-hexylthiophene) hybrid heterojunctions for photovoltaic applications

• Laurie Letertre,
• Roland Roche,
• Olivier Douhéret,
• Hailu G. Kassa,
• Denis Mariolle,
• Nicolas Chevalier,
• Łukasz Borowik,
• Philippe Dumas,
• Benjamin Grévin,
• Roberto Lazzaroni and
• Philippe Leclère

Beilstein J. Nanotechnol. 2018, 9, 2087–2096, doi:10.3762/bjnano.9.197

• frequency shift setpoint and 40 mV of amplitude setpoint. (b) Corresponding KPFM Vcpd image. Vcpd detection parameters: frequency and amplitude of the electrical excitation: 958 Hz and 600 mV. (c) Three-dimensional display of the height image (a), shown with the color scale of the Vcpd (b). (d) Vcpd

• height detection parameters: −5 Hz of frequency shift setpoint and 50 mV of amplitude setpoint. (b) Corresponding KPFM Vcpd image recorded without illumination. KPFM Vcpd detection parameters: frequency and amplitude of the electrical excitation: 958 Hz and 600 mV. (c) Corresponding KPFM Vph image

• -COOH HHJ. KPFM height detection parameters: −10 Hz of frequency shift setpoint and 5 nm of amplitude setpoint. (b) Corresponding KPFM Vcpd image. KPFM Vcpd detection parameters: frequency and amplitude of the electrical excitation: 80 Hz and 500 mV, respectively. 5 × 5 µm2 (a,b) and 500 × 500 nm2 (c,d