Impact of thermal frequency drift on highest precision force microscopy using quartz-based force sensors at low temperatures

• Florian Pielmeier,
• Daniel Meuer,
• Daniel Schmid,
• Christoph Strunk and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2014, 5, 407–412, doi:10.3762/bjnano.5.48

• Florian Pielmeier Daniel Meuer Daniel Schmid Christoph Strunk Franz J. Giessibl Institute of Experimental and Applied Physics, University of Regensburg, D-93053 Regensburg, Germany 10.3762/bjnano.5.48 Abstract In frequency modulation atomic force microscopy (FM-AFM) the stability of the

• detector noise. Keywords: AFM; frequency drift; length extensional resonator; needle sensor; qPlus sensor; quartz; Findings Frequency modulation atomic force microscopy [1] has become an essential tool for surface scientist‘s to study chemical and magnetic interactions at the atomic scale [2][3][4][5][6

Challenges and complexities of multifrequency atomic force microscopy in liquid environments

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 298–307, doi:10.3762/bjnano.5.33

• discussion are mostly applicable to the cases where higher eigenmodes are driven in open loop and frequency modulation within bimodal schemes, but some concepts are also applicable to other types of multifrequency operations and to single-eigenmode amplitude and frequency modulation methods. Keywords

• : amplitude-modulation; bimodal; frequency-modulation; liquids; multifrequency atomic force microscopy; Introduction Multifrequency atomic force microscopy (AFM) refers to a family of techniques that involve simultaneous excitation of the microcantilever probe at more than one frequency [1]. The first of

• extended to intermittent contact characterization using open loop and frequency modulation [3][4], imaging in liquid and vacuum environments [5][6][7][8], and to trimodal operation [9][10][11]. There also exist a number of other multifrequency and multiharmonic AFM techniques which have been developed for

Frequency, amplitude, and phase measurements in contact resonance atomic force microscopies

• Gheorghe Stan and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 278–288, doi:10.3762/bjnano.5.30

• is provided. Keywords: contact-resonance AFM; dynamic AFM; frequency modulation; phase-locked loop; viscoelasticity; Introduction A number of atomic force microscopy (AFM) variants have emerged since the introduction of the original technique in 1986 [1]. Besides topographical acquisition and

• , similar with what is used in non-contact frequency modulation AFM. In non-contact AFM, PLL tracking has been implemented in either constant-excitation frequency modulation [17][18] or constant-amplitude frequency-modulation [19][20]. In the following we will refer only to the constant-excitation PLL setup

Unlocking higher harmonics in atomic force microscopy with gentle interactions

• Sergio Santos,
• Victor Barcons,
• Josep Font and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2014, 5, 268–277, doi:10.3762/bjnano.5.29

• , and by driving with sufficiently small (sub-nanometer) second mode amplitudes, the first mode amplitude [24] or frequency [17] can be employed to track the sample in amplitude or frequency modulation (AM and FM), respectively. The second mode can then be left as an open loop for high sensitivity

Influence of the adsorption geometry of PTCDA on Ag(111) on the tip–molecule forces in non-contact atomic force microscopy

• Gernot Langewisch,
• Jens Falter,
• André Schirmeisen and
• Harald Fuchs

Beilstein J. Nanotechnol. 2014, 5, 98–104, doi:10.3762/bjnano.5.9

• atomic force microscope (Omicron LT-SPM) that was operated in frequency-modulation mode [11] under ultrahigh vacuum conditions and at a temperature of ≈5 K using a tuning fork sensor (resonance frequency f0 = 24640 Hz, spring constant k ≈ 2000 N/m) in the qPlus design [12]. The amplitude of the sensor

Noise performance of frequency modulation Kelvin force microscopy

• Heinrich Diesinger,
• Dominique Deresmes and
• Thierry Mélin

Beilstein J. Nanotechnol. 2014, 5, 1–18, doi:10.3762/bjnano.5.1

• Heinrich Diesinger Dominique Deresmes Thierry Melin Institut d’Electronique, Microélectronique et Nanotechnologie (IEMN), CNRS UMR 8520, CS 60069, Avenue Poincaré, 59652 Villeneuve d’Ascq, France 10.3762/bjnano.5.1 Abstract Noise performance of a phase-locked loop (PLL) based frequency modulation

• general equation yields the approximations for particular cases below that are so frequently found in the literature. It is noteworthy that the phase is generally complex, i.e., the phase difference is itself dephased with respect to the frequency modulation at fpert. For this result, it is irrelevant

• . Consequently, the possible phase excursion may be higher than 90°. Next, the forward response of the PLL, APLL, is studied dynamically. This experiment has to be performed by applying a frequency modulation indirectly since the integrated lock-in module does not allow transfer function measurements by

Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

• Daniel Kiracofe,
• Arvind Raman and
• Dalia Yablon

Beilstein J. Nanotechnol. 2013, 4, 385–393, doi:10.3762/bjnano.4.45

• bistability by using frequency modulation, phase modulation or other newer feedback control schemes, such as drive modulation. From a theoretical point of view, more research is needed to understand the nature of the different states and exactly why the contrast should reverse. The fact that there is no

Optimal geometry for a quartz multipurpose SPM sensor

• Julian Stirling

Beilstein J. Nanotechnol. 2013, 4, 370–376, doi:10.3762/bjnano.4.43

• constant for the tine of the sensor. A combined AFM/LFM sensor operated in frequency modulation mode would enable measurements of conservative and nonconservative forces simultaneously in the normal and lateral direction. Such measurements could be used to further important investigations in single

Bimodal atomic force microscopy driving the higher eigenmode in frequency-modulation mode: Implementation, advantages, disadvantages and comparison to the open-loop case

• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2013, 4, 198–207, doi:10.3762/bjnano.4.20

• Daniel Ebeling Santiago D. Solares Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA 10.3762/bjnano.4.20 Abstract We present an overview of the bimodal amplitude–frequency-modulation (AM-FM) imaging mode of atomic force microscopy (AFM), whereby the

• fundamental eigenmode is driven by using the amplitude-modulation technique (AM-AFM) while a higher eigenmode is driven by using either the constant-excitation or the constant-amplitude variant of the frequency-modulation (FM-AFM) technique. We also offer a comparison to the original bimodal AFM method, in

• provides information and guidelines that can be useful in selecting the most appropriate operation mode to characterize different samples in the most efficient and reliable way. Keywords: amplitude-modulation; atomic force microscopy; frequency-modulation; phase-locked loop; spectroscopy; Introduction

High-resolution dynamic atomic force microscopy in liquids with different feedback architectures

• John Melcher,
• David Martínez-Martín,
• Miriam Jaafar,
• Julio Gómez-Herrero and
• Arvind Raman

Beilstein J. Nanotechnol. 2013, 4, 153–163, doi:10.3762/bjnano.4.15

• with dAFM in liquid media with amplitude modulation (AM), frequency modulation (FM) and drive-amplitude modulation (DAM) imaging modes. We find that while the quality factors of dAFM probes may deviate by several orders of magnitude between vacuum and liquid media, their sensitivity to tip–sample

Towards 4-dimensional atomic force spectroscopy using the spectral inversion method

• Jeffrey C. Williams and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2013, 4, 87–93, doi:10.3762/bjnano.4.10

• force microscopy (AFM) is the measurement of probe–sample interaction force curves (force spectroscopy), generally based on contact and frequency-modulation methods [1][2][3][4][5][6]. The procedure is generally time-consuming because the acquisition of the force curve for each (x,y) location on the

Interpreting motion and force for narrow-band intermodulation atomic force microscopy

• Daniel Platz,
• Daniel Forchheimer,
• Erik A. Tholén and
• David B. Haviland

Beilstein J. Nanotechnol. 2013, 4, 45–56, doi:10.3762/bjnano.4.5

• narrow-band frequency comb. We show, by a separation of time scales, that such motion is equivalent to rapid oscillations at the cantilever resonance with a slow amplitude and phase or frequency modulation. With this time-domain perspective, we analyze single oscillation cycles in ImAFM to extract the

• describe amplitude- and frequency-modulated signals. For frequency modulation we define an instantaneous oscillation phase and an instantaneous oscillation frequency The instantaneous frequency shift δω compared to is then simply In a small region around the time t' the signal x(t) can be obtained by a

• constructed signal with sinusoidally modulated amplitude and frequency. Typical parameters from AFM experiments have been chosen for the amplitude and frequency modulation. The spectrum of the signal shown in Figure 3 shows significant amplitudes at discrete frequencies in only a narrow band around 300 kHz

Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

• Jannis Lübbe,
• Matthias Temmen,
• Sebastian Rode,
• Philipp Rahe,
• Angelika Kühnle and
• Michael Reichling

Beilstein J. Nanotechnol. 2013, 4, 32–44, doi:10.3762/bjnano.4.4

• microscopy (NC-AFM); noise; Introduction In this contribution, we discuss noise in frequency-modulation noncontact atomic force microscopy (NC-AFM) using cantilevers as force sensors and optical beam deflection (OBD) for signal detection. Figure 1 shows a schematic diagram of an NC-AFM setup based on OBD to

• temperature fluctuations and mechanical instability. It has been shown, however, that by operating the laser diode with radio-frequency modulation, the contribution of the light source to the total noise can be reduced to a negligible minimum [3]. The issue of noise is intimately related to the requirements

• here a scanning of the tip over the surface with a speed vt where a periodic corrugation (period as) of the surface Δfm creates a sinusoidal modulation at the frequency fm = vt/as (fm = 30 Hz in Figure 2), i.e., Δf(t) = + Δfmsin(2πfm + φ). Effectively, this is a frequency modulation of Vz(t) with a

Characterization of the mechanical properties of qPlus sensors

• Jan Berger,
• Martin Švec,
• Martin Müller,
• Martin Ledinský,
• Antonín Fejfar,
• Pavel Jelínek and
• Zsolt Majzik

Beilstein J. Nanotechnol. 2013, 4, 1–9, doi:10.3762/bjnano.4.1

• detected frequency modulation. However, a reliable estimation of the measured force depends on several factors, among them the proper calibration of the mechanical properties (stiffness) of the sensor. Originally all mass-produced tuning forks are tuned to the same frequency by laser trimming. However, it

Spring constant of a tuning-fork sensor for dynamic force microscopy

• Dennis van Vörden,
• Manfred Lange,
• Merlin Schmuck,
• Nico Schmidt and
• Rolf Möller

Beilstein J. Nanotechnol. 2012, 3, 809–816, doi:10.3762/bjnano.3.90

• , offering several advantages compared to the standard microfabricated silicon-based cantilevers [1][2]. Frequency-modulation atomic force microscopy (FM-AFM) with a tuning-fork sensor has had a major impact on fundamental and scientific research, e.g., by resolving the structure of a molecule [3] or even

Mapping mechanical properties of organic thin films by force-modulation microscopy in aqueous media

• Jianming Zhang,
• Zehra Parlak,
• Carleen M. Bowers,
• Terrence Oas and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 464–474, doi:10.3762/bjnano.3.53

• . Here, acoustic AFM methods are promising tools since they enable sensitive mapping of the contact-mechanical properties of samples by introducing high-frequency modulation while imaging the topography [53]. Although these methods have been used in air, imaging of many polymers and biomolecules should

Drive-amplitude-modulation atomic force microscopy: From vacuum to liquids

• Miriam Jaafar,
• David Martínez-Martín,
• Mariano Cuenca,
• John Melcher,
• Arvind Raman and
• Julio Gómez-Herrero

Beilstein J. Nanotechnol. 2012, 3, 336–344, doi:10.3762/bjnano.3.38

• microscopy as a dynamic mode with outstanding performance in all environments from vacuum to liquids. As with frequency modulation, the new mode follows a feedback scheme with two nested loops: The first keeps the cantilever oscillation amplitude constant by regulating the driving force, and the second uses

• environments. Drive-amplutide modulation is a very stable, intuitive and easy to use mode that is free of the feedback instability associated with the noncontact-to-contact transition that occurs in the frequency-modulation mode. Keywords: atomic force microscopy; control systems; dissipation; frequency

• high quality factor Q of the cantilevers in vacuum, which present a settling time given by τcl= Q/(πf0). Frequency-modulation AFM (FM-AFM, also known as noncontact AFM) [9] is the classical alternative to AM allowing atomic resolution in UHV chambers [10] at higher scanning rates. FM-AFM has recently

Graphite, graphene on SiC, and graphene nanoribbons: Calculated images with a numerical FM-AFM

• Fabien Castanié,
• Laurent Nony,
• Sébastien Gauthier and
• Xavier Bouju

Beilstein J. Nanotechnol. 2012, 3, 301–311, doi:10.3762/bjnano.3.34

• demonstrates the stability of our n-AFM to image a non-perfectly planar substrate exhibiting a geometrical step as well as a material step. Keywords: calculations; FM-AFM; graphene; graphite; image; nanoribbon; Introduction In the family of atomic force microscopy (AFM) techniques, the frequency-modulation

• substrate, a graphene surface on a SiC substrate, and the edges of graphene nanoribbons, in frozen-atom and free-atom modes. Technical details of the numerical AFM (n-AFM) n-AFM in frequency-modulation mode The n-AFM simulates the behavior of a frequency-modulation AFM with parameters compatible with an

Simultaneous current, force and dissipation measurements on the Si(111) 7×7 surface with an optimized qPlus AFM/STM technique

• Zsolt Majzik,
• Martin Setvín,
• Andreas Bettac,
• Albrecht Feltz,
• Vladimír Cháb and
• Pavel Jelínek

Beilstein J. Nanotechnol. 2012, 3, 249–259, doi:10.3762/bjnano.3.28

• , and reliable interpretation of the atomic contrast becomes very difficult. The next milestone in AFM history was the introduction of the frequency-modulation (FM)-AFM technique by Albrecht and co-workers [4]. By applying this method Giessibl demonstrated the possibility of achieving true atomic

Analysis of force-deconvolution methods in frequency-modulation atomic force microscopy

• Joachim Welker,
• Esther Illek and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 238–248, doi:10.3762/bjnano.3.27

• Joachim Welker Esther Illek Franz J. Giessibl Institute of Experimental and Applied Physics, Experimental Nanoscience, University of Regensburg, Universitaetsstrasse 31, 93053 Regensburg, Germany 10.3762/bjnano.3.27 Abstract In frequency-modulation atomic force microscopy the direct observable is

• Sader–Jarvis method. However, the matrix method generally provides the higher deconvolution quality. Keywords: frequency-modulation atomic force microscopy; force deconvolution; numerical implementation; Introduction The atomic force microscope (AFM) was invented 25 years ago as an offspring of the

• molecules. However, all these remarkable results have to rely on inversion methods as the force is not directly measured in the dynamic modes of an AFM. For high-resolution atomic force microscopy commonly the frequency-modulation (FM) technique is used [6]. In FM-AFM the direct observable is the frequency

An NC-AFM and KPFM study of the adsorption of a triphenylene derivative on KBr(001)

• Antoine Hinaut,
• Adeline Pujol,
• Florian Chaumeton,
• David Martrou,
• André Gourdon and
• Sébastien Gauthier

Beilstein J. Nanotechnol. 2012, 3, 221–229, doi:10.3762/bjnano.3.25

• the development of atomic force microscopy in the noncontact (or frequency modulation) mode [1][2][3][4][5][6][7][8][9][10][11][12][13]. A wide variety of structures, from 3-D islands to single molecules have been observed on different surfaces with an ever-increasing resolution, and there is still

• ], namely the frequency- and amplitude-modulation modes. In this work, we use the frequency-modulation mode. The voltage was modulated at 1 kHz with an amplitude of 2 V. The images were obtained in the constant Δf mode with an oscillation amplitude of A = 2 nm and small values of Δf, corresponding to

A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope

• Manfred Lange,
• Dennis van Vörden and
• Rolf Möller

Beilstein J. Nanotechnol. 2012, 3, 207–212, doi:10.3762/bjnano.3.23

• about 0.22 eV/cycle. Keywords: atomic force microscopy; energy dissipation; force spectroscopy; hysteresis loop; PTCDA/Ag/Si(111) √3 × √3; Introduction Noncontact atomic force microscopy (NC-AFM) is a powerful tool for the study of surface properties. The invention of the frequency-modulation mode (FM

Theoretical study of the frequency shift in bimodal FM-AFM by fractional calculus

• Elena T. Herruzo and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2012, 3, 198–206, doi:10.3762/bjnano.3.22

• frequency shifts in bimodal frequency modulation AFM with the half-derivative of the tip–surface force or, alternatively, with the half-integral of the force gradient. The approximations are valid for the common experimental situation in which the amplitude of the first mode is larger than the length scale

• of the interaction force. The approximations are also valid for two different types of forces, namely Lennard-Jones interactions and DMT contact-mechanics forces. We conclude that the fractional-calculus approach is well suited to describe bimodal frequency modulation AFM experiments, which are

Molecular-resolution imaging of pentacene on KCl(001)

• Julia L. Neff,
• Jan Götzen,
• Enhui Li,
• Michael Marz and
• Regina Hoffmann-Vogel

Beilstein J. Nanotechnol. 2012, 3, 186–191, doi:10.3762/bjnano.3.20

• the surface was kept at room temperature. The rate was approximately 1 Å/min and was monitored by a quartz microbalance. Supersharp silicon cantilevers provided by Nanosensors (Neuchatel, Switzerland) were heated in vacuum to about 390 K to remove contaminants. Frequency-modulation dynamic SFM

qPlus magnetic force microscopy in frequency-modulation mode with millihertz resolution

• Maximilian Schneiderbauer,
• Daniel Wastl and
• Franz J. Giessibl

Beilstein J. Nanotechnol. 2012, 3, 174–178, doi:10.3762/bjnano.3.18

• , which is typically used for MFM. Therefore, we achieved a setup that is able to record a wide range of scanning-probe imaging signals; starting from domain-resolving MFM experiments, culminating in atomically resolved STM and AFM experiments (Figure 1). Results and Discussion In frequency modulation AFM