General Theory of Amplitude-Modulation Atomic Force Microscopy

Lee, Manhee; Jhe, Wonho

doi:10.1103/physrevlett.97.036104

Cited by 133 publications

(135 citation statements)

References 21 publications

(42 reference statements)

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“…The corresponding effective damping force (black curve in Fig. 1C) is calculated by the damped harmonic equation of the tip (13,14).…”

Section: Resultsmentioning

confidence: 99%

“…To address the fundamental mechanism responsible for superwetting, one has to go beyond the contact-angle measurement that reflects the specific surface properties and to probe the temporal growth dynamics of the water layer itself adsorbed on TiO 2 under wide-spectrum illumination of visible and near-infrared (NIR) in addition to UV light. The dynamic atomic force microscopy (12) that employs the stiff and sensitive tip based on the quartz tuning fork (QTF) oscillator (13,14) is an ideal solution to realize the experimental challenge of direct measurement of the growth rate and height, which is inaccessible to the cantilever-based friction force microscopy owing to jump-to-contact instability (1).…”

mentioning

confidence: 99%

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Superwetting of TiO ₂ by light-induced water-layer growth via delocalized surface electrons

Lee

Kim

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Titania, which exhibits superwetting under light illumination, has been widely used as an ideal material for environmental solution such as self-cleaning, water-air purification, and antifogging. There have been various studies to understand such superhydrophilic conversion. The origin of superwetting has not been clarified in a unified mechanism yet, which requires direct experimental investigation of the dynamic processes of water-layer growth. We report in situ measurements of the growth rate and height of the photo-adsorbed water layers by tip-based dynamic force microscopy. For nanocrystalline anatase and rutile TiO 2 we observe light-induced enhancement of the rate and height, which decrease after O 2 annealing. The results lead us to confirm that the long-range attraction between water molecules and TiO 2 , which is mediated by delocalized electrons in the shallow traps associated with O 2 vacancies, produces photo-adsorption of water on the surface. In addition, molecular dynamics simulations clearly show that such photo-adsorbed water is critical to the zero contact angle of a water droplet spreading on it. Therefore, we conclude that this "water wets water" mechanism acting on the photoadsorbed water layers is responsible for the light-induced superwetting of TiO 2 . Similar mechanism may be applied for better understanding of the hydrophilic conversion of doped TiO 2 or other photo-catalytic oxides.

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“…The corresponding effective damping force (black curve in Fig. 1C) is calculated by the damped harmonic equation of the tip (13,14).…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Superwetting of TiO ₂ by light-induced water-layer growth via delocalized surface electrons

Lee

Kim

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…44,45 Over the past decade, methods to reconstruct forces by inverting amplitude and phase shis in standard AM AFM have also been proposed by several groups. [61][62][63] It could be argued however that the most commonly employed method is one presented by Katan and Oosterkamp 64,65 whereby the equivalence of the parameters controlling the dynamics in AM AFM and FM AFM is recognized. Then the relationship between the cosine of the phase shi, the conservative forces and the frequency shi is employed to exploit the standard FM formalism, i.e.…”

Section: 37mentioning

confidence: 99%

“…The standard FM AFM method as well as other proposed methods of force reconstruction in dAFM [61][62][63] make use of the integral form of the equation of motion and are based on the single mode/fundamental harmonic approximation. The most important implication from a practical point of view is that these methods typically require approaching the surface by decreasing the cantilever separation and acquiring data for a range of separations.…”

Section: 37mentioning

confidence: 99%

Single cycle and transient force measurements in dynamic atomic force microscopy

Gadelrab¹,

Santos²,

Font

et al. 2013

Nanoscale

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The monitoring of the deflection of a micro-cantilever, as the end of a sharp probe mounted at its end, i.e. the tip, interacts with a surface, forms the foundation of atomic force microscopy AFM. In a nutshell, developments in the field are driven by the requirement of obtaining ever increasing throughput and sensitivity, and enhancing the versatility of the instrument to simultaneously map the topography and quantify nanoscale processes and properties. In the most common dynamic mode of operation, the motion of the driven cantilever is monitored at a single point on its longitudinal axis. Here, we show that from this single point a waveform is obtained that contains all the details about conservative and dissipative interactions. Then a formalism that accounts for multiple arbitrary flexural modes is developed for an indirectly driven cantilever. The formalism is shown to allow recovery of the details of the interaction even in the presence of complex and relevant hysteretic forces when the cantilever oscillates in the steady state. In a different approach, we develop a formalism that monitors the wave profile of the cantilever, i.e. the waveform at five different points on its longitudinal axis. With this formalism the interaction can be reconstructed during a single oscillation cycle even in the transient state of oscillation. Finally, we discuss the potential and advantages of the proposed methods and future technical challenges. Other standard and state of the art techniques and methods are also discussed and compared with the ones presented here. This work should also provide insight into the current high throughput-high sensitivity developments dealing with multifrequency dynamic AFM where information is recovered from multiple eigenmodes.

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“…10,11 Besides, the tip-sample interaction force reconstruction or force inversion in AM-AFM, an inverse problem in cantilevertip dynamics, has also been studied. [12][13][14][15][16] Meanwhile, in recent years, multifrequency atomic force microscopy (MF-AFM) has attracted more and more attentions from researchers in this field. 17,18 In spite of the above advances achieved in AM-AFM, however, to the authors' knowledge, AM-AFM based on higher flexural modes of a cantilever has never been specially addressed.…”

Section: Introductionmentioning

confidence: 99%

Amplitude modulation atomic force microscopy based on higher flexural modes

et al. 2017

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In this work, amplitude modulation atomic force microscopy (AM-AFM) based on the higher flexural modes of the microcantilever is investigated by a numerical approach. The amplitude-distance and phase-distance curves for the first four flexural modes are obtained and compared. The dependence of phase on elastic modulus and viscosity of the sample is analyzed. Results show that a higher flexural mode yields a larger amplitude and phase in the repulsive regime and reduces the bistability, but causes a larger sample deformation and peak repulsive force. Compared to that of a lower flexural mode, the phase of a higher flexural mode provides higher sensitivity to viscosity variation for relatively large moduli.

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General Theory of Amplitude-Modulation Atomic Force Microscopy

Cited by 133 publications

References 21 publications

Superwetting of TiO ₂ by light-induced water-layer growth via delocalized surface electrons

Superwetting of TiO ₂ by light-induced water-layer growth via delocalized surface electrons

Single cycle and transient force measurements in dynamic atomic force microscopy

Amplitude modulation atomic force microscopy based on higher flexural modes

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General Theory of Amplitude-Modulation Atomic Force Microscopy

Cited by 133 publications

References 21 publications

Superwetting of TiO 2 by light-induced water-layer growth via delocalized surface electrons

Superwetting of TiO 2 by light-induced water-layer growth via delocalized surface electrons

Single cycle and transient force measurements in dynamic atomic force microscopy

Amplitude modulation atomic force microscopy based on higher flexural modes

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Superwetting of TiO ₂ by light-induced water-layer growth via delocalized surface electrons

Superwetting of TiO ₂ by light-induced water-layer growth via delocalized surface electrons