Water distribution at solid/liquid interfaces visualized by frequency modulation atomic force microscopy

Fukuma, Takeshi

doi:10.1088/1468-6996/11/3/033003

Cited by 88 publications

(77 citation statements)

References 72 publications

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“…Although the method was developed using a cryogenic microscope which decreases drift and improves resolution; it does not inherently require low temperatures and has even been extended to liquids. 14 …”

Section: Generating Quantitative Potential Energy Mapsmentioning

confidence: 99%

Noncontact Atomic Force Microscopy: An Emerging Tool for Fundamental Catalysis Research

Altman¹,

Baykara

Schwarz³

2015

Acc. Chem. Res.

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CONSPECTUS:Although atomic force microscopy (AFM) was rapidly adopted as a routine surface imaging apparatus after its introduction in 1986, it has not been widely used in catalysis research. The reason is that common AFM operating modes do not provide the atomic resolution required to follow catalytic processes; rather the more complex noncontact (NC) mode is needed. Thus, scanning tunneling microscopy has been the principal tool for atomic scale catalysis research. In this Account, recent developments in NC-AFM will be presented that offer significant advantages for gaining a complete atomic level view of catalysis. The main advantage of NC-AFM is that the image contrast is due to the very short-range chemical forces that are of interest in catalysis. This motivated our development of 3D-AFM, a method that yields quantitative atomic resolution images of the potential energy surfaces that govern how molecules approach, stick, diffuse, and rebound from surfaces. A variation of 3D-AFM allows the determination of forces required to push atoms and molecules on surfaces, from which diffusion barriers and variations in adsorption strength may be obtained. Pushing molecules towards each other provides access to intermolecular interaction between reaction partners. Following reaction, NC-AFM with CO-terminated tips yields textbook images of intramolecular structure that can be used to identify reaction intermediates and products. Because NC-AFM and STM contrast mechanisms are distinct, combining the two methods can produce unique insight. It is demonstrated for surface-oxidized Cu(100) that simultaneous 3D-AFM/STM yields resolution of both the Cu and O atoms. Moreover, atomic defects in the Cu sublattice lead to variations in the reactivity of the neighboring O atoms. It is shown that NC-AFM also allows a straightforward imaging of work function variations which has been used to identify defect charge states on catalytic surfaces and to map charge transfer within an individual molecule. These advances highlight the potential for NC-AFM-based methods to become the cornerstone upon which a quantitative atomic scale view of each step of a catalytic process may be gained. Realizing this potential will rely on two breakthroughs: (1) development of robust methods for tip functionalization and (2) simplification of NC-AFM instrumentation and control schemes. Quartz force sensors may offer paths forward in both cases. They allow any material with an atomic asperity to be used as a tip, opening the door to a wide range of surface functionalization chemistry. In addition, they do not suffer from the instabilities that motivated the initial adoption of complex control strategies that are still used today.

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Section: Generating Quantitative Potential Energy Mapsmentioning

confidence: 99%

Noncontact Atomic Force Microscopy: An Emerging Tool for Fundamental Catalysis Research

Altman¹,

Baykara

Schwarz³

2015

Acc. Chem. Res.

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“…11,12 The influence from φ d is particularly serious when a high frequency cantilever is used in liquid. φ d increases with increasing ω while ω increases with increasing ω 0 .…”

Section: Frequency-dependent Phase Delaymentioning

confidence: 99%

“…With the setup using the M-PLL, the fastest imaging speed that allows to obtain an image without a significant distortion was 53 s per 3D image ( f m = 200 Hz, 0.32 s per XZ image) as reported previously. 12 With the developed S-PLL using the real-time phase correction circuit, we have been able to obtain a 3D image in 13 s ( f m = 781 Hz, 0.082 s per XZ image) as shown in Fig. 4(b).…”

Section: D Hydration Force Measurementsmentioning

confidence: 99%

“…However, in the case of FM-AFM with a low Q factor and a high frequency cantilever, the frequencydependent phase delay ( φ d ) caused by the other components in the feedback loop is not necessarily negligible, which leads to an error in the measurements of conservative and dissipative forces by FM-AFM. 11,12 Recently, it has become common to use a phase-locked loop (PLL) circuit for producing a cantilever excitation signal as well as for the detection of the frequency shift ( f ) of the cantilever oscillation in FM-AFM. 13 In the previous study, we have presented a design for a high-speed digital PLL with a subtraction-based phase comparator (S-PLL).…”

Section: Introductionmentioning

confidence: 99%

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Wideband phase-locked loop circuit with real-time phase correction for frequency modulation atomic force microscopy

Fukuma

Yoshioka

Asakawa

2011

Review of Scientific Instruments

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We have developed a wideband phase-locked loop (PLL) circuit with real-time phase correction for high-speed and accurate force measurements by frequency modulation atomic force microscopy (FM-AFM) in liquid. A high-speed operation of FM-AFM requires the use of a high frequency cantilever which, however, increases frequency-dependent phase delay caused by the signal delay within the cantilever excitation loop. Such phase delay leads to an error in the force measurements by FM-AFM especially with a low Q factor. Here, we present a method to compensate this phase delay in real time. Combined with a wideband PLL using a subtraction-based phase comparator, the method allows to perform an accurate and high-speed force measurement by FM-AFM. We demonstrate the improved performance by applying the developed PLL to three-dimensional force measurements at a mica/water interface.

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“…Then precise measurement of such short-range chemical force allows to distinguish between different atomic species even though they exhibit very similar chemical properties and identical surface position preferences so that any discrimination attempt based on topographic measurements is impossible (Gross et al, 2009;Lantz et al, 2001;Sugimoto, Pou, Abe, Jelinek, Pérez, Morita & Custance, 2007). Moreover, FM-AFM has recently attained atomic scale resolution in liquids, (Fukuma, 2010;Fukuma et al, 2010).…”

mentioning

confidence: 99%

Wavelet Transforms in Dynamic Atomic Force Spectroscopy

Malegori¹,

Ferrini²

2012

Atomic Force Microscopy - Imaging, Measuring and Manipulating Surfaces at the Atomic Scale

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Water distribution at solid/liquid interfaces visualized by frequency modulation atomic force microscopy

Cited by 88 publications

References 72 publications

Noncontact Atomic Force Microscopy: An Emerging Tool for Fundamental Catalysis Research

Noncontact Atomic Force Microscopy: An Emerging Tool for Fundamental Catalysis Research

Wideband phase-locked loop circuit with real-time phase correction for frequency modulation atomic force microscopy

Wavelet Transforms in Dynamic Atomic Force Spectroscopy

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