Observation of 4 nm Pitch Stripe Domains Formed by Exposing Graphene to Ambient Air

Wastl, Daniel S.; Speck, Florian; Wutscher, Elisabeth; Ostler, Markus; Seyller, Thomas; Giessibl, Franz J.

doi:10.1021/nn403988y

Cited by 54 publications

(83 citation statements)

References 55 publications

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“…Images with a size of 2 lm 9 2 lm were recorded with a noncontact atomic force microscope using qPlus force sensors [15][16][17]. The imaging technique was frequency modulation AFM [18].…”

Section: Surface Roughness Analysismentioning

confidence: 99%

Influence of matrix and filler fraction on biofilm formation on the surface of experimental resin-based composites

Ionescu

Brambilla

Wastl

et al. 2015

J Mater Sci: Mater Med

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The aim of this study was to investigate the impact of resin matrix chemistry and filler fraction on biofilm formation on the surface of experimental resin-based composites (RBCs). Specimens were prepared from eight experimental RBC formulations differing in resin matrix blend (BisGMA/TEGDMA in a 7:3 wt% ratio or UDMA/aliphatic dimethacrylate in a 1:1 wt% ratio) and filler fraction (no fillers; 65 wt% dental glass with an average diameter of 7 or 0.7 µm or 65 wt% SiO2 with an average diameter of 20 nm). Surface roughness, surface free energy, and chemical surface composition were determined; surface topography was visualized using atomic force microscopy. Biofilm formation was simulated under continuous flow conditions for a 48 h period using a monospecies Streptococcus mutans and a multispecies biofilm model. In the monospecies biofilm model, the impact of the filler fraction overruled the influence of the resin matrix, indicating lowest biofilm formation on RBCs with nano-scaled filler particles and those manufactured from the neat resin blends. The multispecies model suggested a more pronounced effect of the resin matrix blend, as significantly higher biofilm formation was identified on RBCs with a UDMA/dimethacrylate matrix blend than on those including a BisGMA/TEGDMA matrix blend but analogous filler fractions. Although significant differences in surface properties between the various materials were identified, correlations between the surface properties and biofilm formation were poor, which highlights the relevance of surface topography and chemistry. These results may help to tailor novel RBC formulations which feature reduced biofilm formation on their surface.

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“…Images with a size of 2 lm 9 2 lm were recorded with a noncontact atomic force microscope using qPlus force sensors [15][16][17]. The imaging technique was frequency modulation AFM [18].…”

Section: Surface Roughness Analysismentioning

confidence: 99%

Influence of matrix and filler fraction on biofilm formation on the surface of experimental resin-based composites

Ionescu

Brambilla

Wastl

et al. 2015

J Mater Sci: Mater Med

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“…In 2D crystals however the interface to the air is formed by all of their atoms. This makes the function of devices using these strongly depending on their surface qualities and so creates a need for improved inline control (Emtsev et al, ; Wastl et al, ), while processing devices, which could be offered by ambient atomic resolution AFM.…”

Section: Introductionmentioning

confidence: 99%

“…In general every tip material and tip geometry is possible (Giessibl, ; Pielmeier & Giessibl, ; Schneiderbauer et al, ; Wastl et al, , , ; Wastl, Speck, Wutscher, & Ostler, ). This opens the way for a huge variety of different experiments and allows a much more precise adaption of the measurements to different problems (Pielmeier & Giessibl, ; Wastl et al, , , ). Several tip materials are often better suitable in an experiment like standard silicon tips of micro fabricated cantilevers.…”

Section: Introductionmentioning

confidence: 99%

“…While approaching the tip closer to the sample it enters different environmental circumstances (see Figure ): first the gas–liquid interface is penetrated (

Q_{1}, {Δ E}_{1}

, green striped line in Figure ), second the liquid part of the condensation layer (

Q_{l i q u i d}, Δ E_{l i q u i d}

blue‐shaded region in Figure ) is entered by the end of the tip, approaching further, one or several sample interface layers (

Q_{2}, Δ E_{2}, \dots, Q_{x}, Δ E_{x},

red dotted line in Figure ) can contribute to

Q_{t s}, Δ E_{t s}

. The sample interface layers are dependent on the nature of the sample and the environmental circumstances (Israelachvili & Pashley, ; Israelachvili & Wennerström, ; Kilpatrick, Loh, & Jarvis, ; Lu, Yang, & Hwang, ; Wastl et al, , , , ). On hydrophobic samples like highly oriented pyrolytic graphite or graphene water layers and gas domains are existing on the surface and can create a layered system (Lu et al, ; Wastl et al, , ).…”

Section: Introductionmentioning

confidence: 99%

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Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1

Wastl

2016

Microscopy Res & Technique

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Atomic force microscopy (AFM) is an enormous tool to observe nature in highest resolution and understand fundamental processes like friction and tribology on the nanoscale. Atomic resolution in highest quality was possible only in well-controlled environments like ultrahigh vacuum (UHV) or controlled buffer environments (liquid conditions) and more specified for long-term high-resolution analysis at low temperatures (∼4 K) in UHV where drift is nearly completely absent. Atomic resolution in these environments is possible and is widely used. However, in uncontrolled environments like air, with all its pollutants and aerosols, unspecified thin liquid films as thin as a single molecular water-layer of 200 pm or thicker condensation films with thicknesses up to hundred nanometer, have been a problem for highest resolution since the invention of the AFM. The goal of true atomic resolution on hydrophilic as well as hydrophobic samples was reached recently. In this manuscript we want to review the concept of ambient AFM with atomic resolution. The reader will be introduced to the phenomenology in ambient conditions and the problems will be explained and analyzed while a method for scan parameter optimization will be explained. Recently developed concepts and techniques how to reach atomic resolution in air and ultra-thin liquid films will be shown and explained in detail, using several examples. Microsc. Res. Tech. 80:50-65, 2017. © 2016 Wiley Periodicals, Inc.

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“…Among these dynamical techniques, of particular interest is frequency-modulation AFM (FM-AFM), which overcomes the stability problem in static AFM, possesses a faster time response than amplitude-modulation AFM, and exhibits a higher sensitivity than any other AFM imaging mode [2] . This technique is presently widely employed in a variety of fields of surface sciences [3][4][5][6][7][8][9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Re-evaluation of the widely applied force-frequency relation for frequency-modulation AFM under solution

Sun

et al. 2014

J. Shanghai Jiaotong Univ. (Sci.)

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Frequency-modulation atomic force microscopy (FM-AFM) is a highly versatile tool for surface science. Besides imaging surfaces, FM-AFM is capable of measuring interactions between the AFM probe and the surface with high sensitivity, which can provide chemical information at sub-nanometer resolution. This is achieved by deconvoluting the frequency shift, which is directly measured in experiments, into the force between the probe and sample. At present, the widely used method to perform this deconvolution has been shown to be accurate under high quality (high-Q) factor vacuum conditions. However, under low quality (low-Q) factor conditions, such as in solution, it is not clear if this method is valid. A previous study apparently verified this relation for experiments in solution by comparing the force calculated by this equation with that obtained in separate experiments using the surface force apparatus (SFA). Here we show that, in solution, a more direct comparison of the force calculated by this relation with that directly measured by the cantilever deflection in AFM reveals significant differences, both qualitative and quantitative. However, we also find that there are complications that hinder this comparison. Namely, while contact with the surface is clear in the direct measurements (including the SFA data), it is less certain in the FM-AFM case. Hence, it is not clear if the two methods are measuring the same tip-sample distance regimes. Thus, our results suggest that a more thorough verification of this relation is required, as application of this formulation for experiments in solution may not be valid.

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Observation of 4 nm Pitch Stripe Domains Formed by Exposing Graphene to Ambient Air

Cited by 54 publications

References 55 publications

Influence of matrix and filler fraction on biofilm formation on the surface of experimental resin-based composites

Influence of matrix and filler fraction on biofilm formation on the surface of experimental resin-based composites

Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1

Re-evaluation of the widely applied force-frequency relation for frequency-modulation AFM under solution

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