Structure of the neopentane monolayer adsorbed on MgO(001): experiments and calculations

Trabelsi, Mohsen; Saïdi, Sami; Chefi, C.; Picaud, Sylvain; Hoang, P.N.M.; Coulomb, J.P.

doi:10.1016/j.susc.2003.12.029

Cited by 3 publications

(3 citation statements)

References 15 publications

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“…Importantly, and in a marked difference to the behavior on graphite, the parallel structure persists over the entire composition range for h-BN (cf. Figures 3,5,7,and 8). Thus, unlike on graphite, the ability of n-decane to adopt both structure types on h-BN directly improves the miscibility of these alkanes.…”

Section: ■ Resultsmentioning

confidence: 97%

“…For MgO, it was shown that the adsorption of butane leads to very similar monolayer structures to those identified for graphite despite considerable differences in surface symmetry and chemical composition . Various other short-chain n -alkanes have also now been studied on MgO, ,− although, in most cases, their detailed structures are yet to be published.…”

Section: Introductionmentioning

confidence: 99%

“…Molecular physisorption has been extensively studied on a wide range of surfaces using many different techniques. Some examples include studies of adsorption on single crystals, quasi-crystals as well as on powder substrates. − This latter category of materials has allowed the use of bulk rather than surface specific techniques and has largely concentrated on powdered graphite materials. A large body of literature exists containing detailed information on the structural, thermodynamic, and physical properties of such adsorbed molecular films, and this is well-summarized in the recent reviews by Bruch et al and others. − The adsorption of n -alkanes on graphite has attracted particular interest due to both their technological relevance and the fact that they provide a series of systematically varying molecules, which allows the subtle effects of molecule–substrate and intermolecular interactions to be probed.…”

Section: Introductionmentioning

confidence: 99%

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The Mixing Behavior of Alkanes Adsorbed on Hexagonal Boron Nitride

et al. 2016

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In this work, we report the mixing behavior of a series of normal alkanes adsorbed on the surface of hexagonal boron nitride (h-BN) using X-ray powder diffraction. We have investigated a range of simple binary mixtures which are indicative of a rich phase behavior with examples of complete mixing, partial mixing, and phase separation. On graphite surfaces, the mixing behavior is strongly influenced by the structure of the pure components; the odd−even effect seen in the pure structures, which favors either a "herringbone" or a "parallel" structure, influences the miscibility of alkanes within the monolayer. On h-BN, a more complex phase behavior is observed with partial mixing or phase separation depending upon the exact composition of the monolayer. In particular, we see improved miscibility for certain mixtures containing n-decane which we associate with the fact that pure n-decane has been observed with both herringbone and parallel structures on h-BN. This difference between these two very similar substrates is a sensitive indicator of the subtle interplay between surface−molecule and molecule−molecule interactions that govern the phase behavior of these systems.

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Section: ■ Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Mixing Behavior of Alkanes Adsorbed on Hexagonal Boron Nitride

et al. 2016

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Enthalpies and Entropies of Adsorption on Well-Defined Oxide Surfaces: Experimental Measurements

2013

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The Entropies of Adsorbed Molecules

2012

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Adsorbed molecules are involved in many reactions on solid surface that are of great technological importance. As such, there has been tremendous effort worldwide to learn how to predict reaction rates and equilibrium constants for reactions involving adsorbed molecules. Theoretical calculation of both the rate and equilibrium constants for such reactions requires knowing the entropy and enthalpy of the adsorbed molecule. While much effort has been devoted to measuring and calculating the enthalpies of well-defined adsorbates, few measurements of the entropies of adsorbates have been reported. We present here a new way to determine the standard entropies of adsorbed molecules (S(ad)(0)) on single crystal surfaces from temperature programmed desorption data, prove its accuracy by comparison to entropies measured by equilibrium methods, and apply it to published data to extract new entropies. Most importantly, when combined with reported entropies, we find that at high coverage, they linearly track the entropy of the gas-phase molecule at the same temperature (T), such that S(ad)(0)(T) = 0.70 S(gas)(0)(T) - 3.3R (R = the gas constant), with a standard deviation of only 2R over a range of 50R. These entropies, which are ~2/3 of the gas, are huge compared to most theoretical predictions. This result can be extended to reliably predict prefactors in the Arrhenius rate constant for surface reactions involving such species, as proven here for desorption.

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Structure of the neopentane monolayer adsorbed on MgO(001): experiments and calculations

Cited by 3 publications

References 15 publications

The Mixing Behavior of Alkanes Adsorbed on Hexagonal Boron Nitride

The Mixing Behavior of Alkanes Adsorbed on Hexagonal Boron Nitride

Enthalpies and Entropies of Adsorption on Well-Defined Oxide Surfaces: Experimental Measurements

The Entropies of Adsorbed Molecules

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