How flat is an air-cleaved mica surface?

Ostendorf, Frank; Schmitz, C.; Hirth, Sabine; Kühnle, Angelika; Kołodziej, Jacek; Reichling, Michael

doi:10.1088/0957-4484/19/30/305705

Cited by 103 publications

(106 citation statements)

References 33 publications

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“…Several previous studies [82; 135; 136; 138] were in agreement that the carbonaceous overlayer formed on cleaving mica in air could not be removed by exposure to UHV conditions. Ostendorf et al carried out a comparative AFM study of mica cleaved in air and in UHV, and found very different results with the two samples of different origin [141]. The surface cleaved in UHV could not be satisfactorily imaged in non-contact mode due to the magnitude of the surface potential, typically between -80 and -130 V. The potential could not be reduced by annealing in UHV, even at 560 K, but after a few minutes exposure to air the potential decreased to ±2.5 V. The subsequent AFM images revealed the presence of numerous particles on the surface, of lateral size in the range 1-5 nm, and the authors suggested that these were the K2CO3 crystallites previously observed by one of us [125].…”

Section: Surface Analytical Studies Of Air-cleaved and Vacuum-cleavedmentioning

confidence: 99%

The nature of the air-cleaved mica surface

Christenson

Thomson

2016

Surface Science Reports

114

102

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The accepted image of muscovite mica is that of an inert and atomically smooth surface, easily prepared by cleavage in an ambient atmosphere. Consequently, mica is extensively used a model substrate in many fundamental studies of surface phenomena and as a substrate for AFM imaging of biomolecules. In this review we present evidence from the literature that the above picture is not quite correct. The mica used in experimental work is almost invariably cleaved in laboratory air, where a reaction between the mica surface, atmospheric CO2 and water occurs immediately after cleavage. The evidence suggests very strongly that as a result the mica surface becomes covered by up to one formula unit of K2CO3 per nm 2 , which is mobile under humid conditions, and crystallizes under drier conditions. The properties of mica in air or water vapour cannot be fully understood without reference to the surface K2CO3, and many studies of the structure of adsorbed water on mica surfaces may need to be revisited. With this new insight, however, the air-cleaved mica should provide exciting opportunities to study phenomena such as two-dimensional ion diffusion, electrolyte effects on surface conductivity, and two-dimensional crystal nucleation.

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Section: Surface Analytical Studies Of Air-cleaved and Vacuum-cleavedmentioning

confidence: 99%

The nature of the air-cleaved mica surface

Christenson

Thomson

2016

Surface Science Reports

114

102

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“…Taylor and Schwartz [27] and Lim et al [28] have both used ex-situ AFM to study the films formed by fatty acid solution on alumina. Taylor and Schwartz studied film formation by octadecanoic acid from hexadecane.…”

Section: Afm Studies Of Carboxylic Acid Self-assemblymentioning

confidence: 99%

In Situ Study of Model Organic Friction Modifiers Using Liquid Cell AFM; Saturated and Mono-unsaturated Carboxylic Acids

et al. 2015

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Fatty acids and their derivatives have been used as model organic friction modifiers for almost a century, but there is still debate as to the nature of the boundary films that they form on rubbed surfaces. In this study, in situ liquid cell atomic force microscopy (AFM) is used to monitor the self-assembly of boundary films from solutions of fatty acids in alkanes on to mica surfaces. Because the mica surfaces are wholly immersed in solution it is possible to study directly changes in the morphology and friction of these films over time and during heating and cooling.It has been found that stearic and elaidic acid, that are able to adopt a linear molecular configurations, form irregular islands on mica that are tens to hundreds of microns in diameter and typically 1.6 nm thick, corresponding to domains of tilted single monolayers. At a relatively high concentration of 0.01M, stearic acid in hexadecane forms an almost complete monolayer, but at lower concentrations, in dodecane solution and for elaidic acid solutions these films remain incomplete after prolonged immersion of more than a day. The films formed by fatty acids on mica are displaced by repeated scanning in contact mode AFM but can be imaged without damage using tapping mode AFM.Rubbed quartz surfaces from a sliding ball-on-disc test were also scanned ex-situ using AFM and these showed that stearic acid forms similar monolayer island films on quartz in macroscale friction experiments as are found on mica.Oleic acid solutions behave quite differently from stearic acid and elaidic acid, forming irregular globular films on both mica and rubbed quartz surfaces. This is believed to be because its cis-double bond geometry means that, unlike its trans-isomer elaidic acid or saturated stearic acid, it is unable to adopt a linear molecular configuration and so is less able to form close-packed monolayers.

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“…32 Moreover, the surface potential of mica cleaved under ultra high vacuum (UHV) conditions is up to two orders of magnitude higher than that for mica cleaved in air. 33 Therefore, we suppose that the strong charging of UHV-cleaved mica is associated with the presence of non uniformly distributed K + ions over the mica surface.…”

Section: B Surface Structuresmentioning

confidence: 99%

Graphene adhesion on mica: Role of surface morphology

et al. 2011

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We investigate theoretically the adhesion and electronic properties of graphene on a muscovite mica surface using the density functional theory (DFT) with van der Waals (vdW) interactions taken into account (the vdW-DF approach). We found that irregularities in the local structure of cleaved mica surface provide different mechanisms for the mica-graphene binding. By assuming electroneutrality for both surfaces, the binding is mainly of vdW nature, barely exceeding thermal energy per carbon atom at room temperature. In contrast, if potassium atoms are non uniformly distributed on mica, the different regions of the surface give rise to n-or p-type doping of graphene. In turn, an additional interaction arises between the surfaces, significantly increasing the adhesion. For each case the electronic states of graphene remain unaltered by the adhesion. It is expected, however, that the Fermi level of graphene supported on realistic mica could be shifted relative to the Dirac point due to asymmetry in the charge doping. Obtained variations of the distance between graphene and mica for different regions of the surface are found to be consistent with recent atomic force microscopy experiments. A relative flatness of mica and the absence of interlayer covalent bonding in the mica-graphene system make this pair a promising candidate for practical use.

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How flat is an air-cleaved mica surface?

Cited by 103 publications

References 33 publications

The nature of the air-cleaved mica surface

The nature of the air-cleaved mica surface

In Situ Study of Model Organic Friction Modifiers Using Liquid Cell AFM; Saturated and Mono-unsaturated Carboxylic Acids

Graphene adhesion on mica: Role of surface morphology

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