Solvation and squeeze out of hexadecane on graphite

Gosvami, Nitya Nand; Sinha, S. K.; Hofbauer, Wulf; O'Shea, SJ

doi:10.1063/1.2741538

Cited by 30 publications

(46 citation statements)

References 22 publications

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“…The good fit of the current vs force data to the DMT model shows that in the slow varying current region, change in the tip-sample contact area is the principal cause of the observed variation in current flow. This is entirely similar to observations in hexadecane [22] and indicates that squalane also behaves as an elastic, solid-like monolayer at 25 C. We confirm this by STM imaging of the squalane monolayer, which reveals ordered domains of lamellar structures [ Fig. 3(a)].…”

supporting

confidence: 74%

“…(1)] again provides a good fit to the data. Thus, as shown previously for contacts in hexadecane [22], the relative change in contact area of the tip-HOPG junction is well described by an elastic continuum model. The tip-HOPG contact mechanics is very different in HMN [ Fig.…”

Section: Prl 100 076101 (2008) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 56%

“…0). This behavior is similar to that observed for a hexadecane monolayer on HOPG [22]. We can model the slow varying region using continuum elastic mechanics, assuming the current is proportional to the tip-sample contact area [22].…”

mentioning

confidence: 60%

“…where A is a proportionality constant, I is the measured current, R is the tip radius of curvature, F is the applied force, F c is the pull-off force, and K is the effective modulus for the gold-HOPG system (39.5 GPa [22]). The good fit of the current vs force data to the DMT model shows that in the slow varying current region, change in the tip-sample contact area is the principal cause of the observed variation in current flow.…”

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confidence: 99%

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Squeeze-Out of Branched Alkanes on Graphite

2008

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We study squalane and heptamethylnonane (HMN) confined between a conducting atomic force microscope tip and a graphite surface. Solvation layering occurs for both liquids but marked differences in the squeeze out mechanics are observed for ordered or disordered monolayers. The squalane monolayer at 25 C is an ordered solid, as verified by direct imaging, and the squeeze out can be modeled using elastic continuum mechanics. HMN is in a disordered state at 25 C and cannot be modeled as a single elastic asperity even in solid-solid contact because HMN liquid is trapped in the contact zone.

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supporting

confidence: 74%

Section: Prl 100 076101 (2008) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 56%

mentioning

confidence: 60%

mentioning

confidence: 99%

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Squeeze-Out of Branched Alkanes on Graphite

2008

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“…This is because surface specific interactions can orient the molecules (see also alcohols on mica [35][36][37] vs HOPG [25]). When a liquid is strongly layered at the surface, the measured periodicity can also be smaller than the molecular size [98]. Before the rupture process the molecular layers can be significantly compressed.…”

Section: ) Shape Of the Oscillatory Solvation Forcesmentioning

confidence: 99%

Probing the properties of confined liquids

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Load‐Dependent Friction Hysteresis for Graphitic Surfaces in n‐Hexadecane

Baboukani

Pitkar

et al. 2022

Adv Materials Inter

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behavior that is dependent on the sliding history of the contact, which currently remains unexplored and is the focus of the current study.Generating a comprehensive understanding of the dissipation pathways for 2D materials in liquids is crucial for developing predictive models for the friction and wear behavior of 2D materials. [11] The atomic force microscope (AFM) has proven to be a unique and powerful tool to investigate the atomic origins of friction behavior of 2D materials under a well-defined, single-asperity contact and in the absence of wear. Previous experiments using AFM in a dry environment showed that the probe sliding history on the 2D material leads to several unique behaviors such as frictional aging of the contact, [12,13] friction strengthening, [14][15][16][17] and load-dependent friction hysteresis. [18][19][20] The previous load-dependent friction measurements on supported graphene reported lower friction forces while increasing the normal load (loading) than when the load was withdrawn (unloading) at a given normal load, [18,19] displaying friction hysteresis. This behavior is shown to originate from the irreversible transformation of the contact upon loading, caused either by changes in the contact area and/or interaction forces at the sliding interface. [18] Several physical parameters, such as the presence of environmental adsorbates, [21] maximum applied load, [19] temperature, [22] sliding velocity, [23] etc., have been shown to influence the sliding-history-dependent friction behavior for single and as well for few-layer (FL) graphene.In ambient or dry conditions, sliding an AFM probe across the graphene deposited on a copper substrate led to an out-of-theplane deformation of the graphene adjacent to the AFM probe. A higher adhesion during the unloading process, in comparison to loading, resulted in delayed relaxation of the graphene layer (higher contact area) and hence enhanced friction hysteresis. [19] However, the presence of condensed water at the probe-graphene contact suppressed the out-of-plane deformation of graphene but instead led to an irreversible reorganization of water molecules at the contact once loaded. [18] The contact area hysteresis, i.e., the smaller number of water molecules in contact with the probe (contact area) during the loading process, in comparison to unloading, led to friction hysteresis of graphene in a humid environment. [18] The load-dependent friction hysteresis was also observed for bulk graphitic surfaces when the work of adhesion between the AFM probe and the graphitic surface exceeded the Sliding-induced friction behavior of a single-asperity silica probe against fewlayer (FL) graphene and bulk graphite is measured in the presence of n-hexadecane using an atomic force microscope (AFM). The load-dependent nanoscale friction measurements display friction hysteresis, i.e., higher friction forces during unloading of the contact than loading, at a given normal load. However, unlike hysteresis in friction of graphene measured in ambient, several uniq...

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Solvation and squeeze out of hexadecane on graphite

Cited by 30 publications

References 22 publications

Squeeze-Out of Branched Alkanes on Graphite

Squeeze-Out of Branched Alkanes on Graphite

Probing the properties of confined liquids

Load‐Dependent Friction Hysteresis for Graphitic Surfaces in n‐Hexadecane

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