The Surface Chemistry of Dimethyl Disulfide on Copper

Furlong, Octavio Javier; Miller, Brendan; Li, Zhenjun; Walker, Joshua D.; Burkholder, Luke; Tysoe, Wilfred T.

doi:10.1021/la101769y

Cited by 36 publications

(75 citation statements)

References 50 publications

(60 reference statements)

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“…The width of the silver wire is also indicated DMDS is selected for these experiments for a number of reasons. It reacts rapidly with copper at *100 K via facile cleavage of the S-S bond to deposit thiolate species (CH 3 -S) on the surface, which are stable to *450 K and decompose to desorb methane and deposit sulfur atoms on the surface [14]. The thiolate monolayer is bonded to the surface via the sulfur atom, with the methyl group oriented away from the surface.…”

Section: Resultsmentioning

confidence: 99%

“…This ensures that there is no change in the nature of the contact region for tribological experiments performed after dosing the surface and produces a *150 lm wide wear track. The copper surface was then exposed to DMDS at 300 K to form a saturated overlayer of methyl thiolate species [14]. Figure 2a, profile I shows the resulting profile across the wear track of the S LMM Auger (with a kinetic energy of 152 eV) peak-to-peak intensity ratioed to that of the copper LMM Auger peak (with a kinetic energy of 920 eV), where the center of the wear track is located at *300 lm.…”

Section: Resultsmentioning

confidence: 99%

“…Once in UHV, copper foils were cleaned using a standard procedure which consisted of argon ion bombardment with a uniform ion flux (*1 kV, *2 lA/cm 2 ) and annealing cycles up to *850 K in vacuo, to remove any surface damage induced by polishing or argon ion bombardment. This process results in a surface that produces a square (1 9 1) low-energy electron diffraction pattern and is therefore well ordered [14]. The cleanliness of the samples was monitored using Auger spectroscopy.…”

Section: Methodsmentioning

confidence: 99%

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Shear-Induced Surface-to-Bulk Transport at Room Temperature in a Sliding Metal–Metal Interface

2010

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Predictions from molecular dynamics (MD) simulations, that sliding at a metal-metal interface causes vortices in the near-surface region that transport atoms from the surface into the subsurface region, is tested experimentally. This is accomplished by rubbing a methyl thiolate overlayer grown on a clean copper foil by exposure to dimethyl disulfide at room temperature. Repeatedly rubbing a 1.27 9 10 -2 m diameter pin over a thiolatecovered copper surface at an applied load of 0.44 N and sliding speed of 4 9 10 -3 m/s in an ultrahigh vacuum tribometer, results in the removal of sulfur from the wear track as measured using spatially resolved Auger spectroscopy. Any remaining surface species, in particular, outside the wear track, are removed by argon ion bombardment. Since sulfur is more thermodynamically stable at the surface, heating the sample causes the sulfur to resegregate to the surface only inside the wear track, thereby directly confirming the predictions from MD simulations.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Shear-Induced Surface-to-Bulk Transport at Room Temperature in a Sliding Metal–Metal Interface

2010

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“…The surface chemistry of DMDS on copper was studied in UHV using a number of surface-sensitive techniques, including temperature-programmed desorption (TPD), 63 X-ray photoelectron spectroscopy, 62 and reection-absorption infrared spectroscopy (RAIRS). 34 These experiments reveal that DMDS adsorbs molecularly on copper at $80 K, but heating to $200 K causes S-S bond scission to form methyl thiolate (CH 3 -S-) species on the surface. The methyl thiolate species are stable up to $426 K, where they thermally decompose to desorb methane along with some ethylene and ethane.…”

Section: Surface Reactions Of Dimethyl Disulde With Coppermentioning

confidence: 98%

Shear and thermal effects in boundary film formation during sliding

et al. 2014

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A prerequisite for understanding mechano-and tribochemical reaction pathways is that the interface be in thermodynamic equilibrium and that the temperature be well defined. It is suggested that this occurs in two regimes: when the surfaces are only slightly perturbed during sliding, leading to negligible frictional heating, and when the surface temperatures are very high ($1000 K), in the so-called extreme pressure regime. The tribochemistry occurring in each regime is discussed in terms of the elementary steps leading to tribofilm formation, namely (i) a reaction of the additive or gas-phase lubricant on the surface to form an adsorbed precursor, (ii) decomposition of the molecular precursor, (iii) a process that causes the formation of a tribofilm that (iv) regenerates a clean surface that allows this tribochemical cycle to continue to form a thicker film. These steps are thermally driven in the extreme-pressure regime, while under milder conditions, they are induced by interfacial shear. In intermediate situations, the processes are likely to be a combination of those occurring at the extrema.

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“…However, it has been shown that these clean and annealed copper foils exhibit sufficient order to display distinct low-energy electron diffraction (LEED) patterns indicating that the surface is ordered. [45]…”

Section: Rtmentioning

confidence: 99%

Surface Chemistry at the Solid‐Solid Interface; Selectivity and Activity in Mechanochemical Reactions on Surfaces

et al. 2021

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This paper summarizes the concepts that underpin the way in which forces exerted on chemical systems can either accelerate their rates or induce reaction pathways that cannot be accessed thermally. This was first described in 1935 by Evans and Polanyi who showed how hydrostatic pressure could accelerate the rates of chemical reactions using a thermodynamic analysis of transition-state theory to demonstrate that the reaction rate increased exponentially with pressure, and depends on a socalled activation volume. This is typically~17 Å 3 /molecule and indicates that pressures on the order of GPa's are required to accelerate the rates of chemical reactions, which commonly occur at solid-solid interfaces such as found in a ball mill. We describe how surface mechanochemical reaction mechanisms are studied using the example of the shear-induced decomposition of carboxylates on copper. They thermally decompose on heating to~650 K to evolve carbon dioxide and deposit a hydrocarbon on the surface but shear stresses accelerate the rate of this process so that it occurs at room temperature. However, it is also found that forces parallel to the COO plane induce a non-thermal reaction pathway to evolve carbon monoxide and adsorbed oxygen on the surface. This reaction pathway can be quenched by using adsorbed benzoate species because the larger area of the aryl ring accentuates the tilt of the COO plane towards the surface to increase the rate of the thermal reaction.

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The Surface Chemistry of Dimethyl Disulfide on Copper

Cited by 36 publications

References 50 publications

Shear-Induced Surface-to-Bulk Transport at Room Temperature in a Sliding Metal–Metal Interface

Shear-Induced Surface-to-Bulk Transport at Room Temperature in a Sliding Metal–Metal Interface

Shear and thermal effects in boundary film formation during sliding

Surface Chemistry at the Solid‐Solid Interface; Selectivity and Activity in Mechanochemical Reactions on Surfaces

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