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Ordered phases of ethylene adsorbed on charged fullerenes and their aggregates.

Zöttl S, Kaiser A, Daxner M, Goulart M, Mauracher A, Probst M, Hagelberg F, Denifl S, Scheier P, Echt O - Carbon N Y (2014)

Bottom Line: Experimental data also reveal the number of molecules in groove sites of the C60 dimer through tetramer.The identity of the sites, adsorption energies and orientations of the adsorbed molecules are determined by molecular dynamics calculations based on quantum chemical potentials, as well as density functional theory.The decrease in orientational order with increasing temperature is also explored in the simulations whereas in the experiment it is impossible to vary the temperature.

View Article: PubMed Central - PubMed

Affiliation: Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.

ABSTRACT

In spite of extensive investigations of ethylene adsorbed on graphite, bundles of nanotubes, and crystals of fullerenes, little is known about the existence of commensurate phases; they have escaped detection in almost all previous work. Here we present a combined experimental and theoretical study of ethylene adsorbed on free C60 and its aggregates. The ion yield of [Formula: see text] measured by mass spectrometry reveals a propensity to form a structurally ordered phase on monomers, dimers and trimers of C60 in which all sterically accessible hollow sites over carbon rings are occupied. Presumably the enhancement of the corrugation by the curvature of the fullerene surface favors this phase which is akin to a hypothetical 1 × 1 phase on graphite. Experimental data also reveal the number of molecules in groove sites of the C60 dimer through tetramer. The identity of the sites, adsorption energies and orientations of the adsorbed molecules are determined by molecular dynamics calculations based on quantum chemical potentials, as well as density functional theory. The decrease in orientational order with increasing temperature is also explored in the simulations whereas in the experiment it is impossible to vary the temperature.

No MeSH data available.


Related in: MedlinePlus

Relative orientation of neighboring C2H4 molecules for the 1 × 1 phase on C60. The angle γ measures the orientation between the two CC axis of two C2H4 molecules, corrected for a tilt due to the curvature. γ is produced by projection of the second CC– axis on the second fullerene face and further projection on the first fullerene face. A detailed definition of γ is given in the text. (A colour version of this figure can be viewed online.)
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f0040: Relative orientation of neighboring C2H4 molecules for the 1 × 1 phase on C60. The angle γ measures the orientation between the two CC axis of two C2H4 molecules, corrected for a tilt due to the curvature. γ is produced by projection of the second CC– axis on the second fullerene face and further projection on the first fullerene face. A detailed definition of γ is given in the text. (A colour version of this figure can be viewed online.)

Mentions: The analysis starts with an annealed and optimized C60Et32 aggregate; with a complete first shell and all molecules in hollow sites. The initial structure is heated up 1 K at a time. In each step of the MD simulation an equilibration period of 2 ps is followed by a production run of 2 ps during which the three angles α, β and γ are evaluated. The distributions of α and β versus temperature are displayed in Fig. 7; the distribution of γ in Fig. 8. The color scale of the 2D histograms is chosen so that small occupation numbers (white and dark blue) are visible as well as peaks (yellow and red). Each column, representing an interval of 1 K, is normalized with its total sum and the total maximum of all counts.


Ordered phases of ethylene adsorbed on charged fullerenes and their aggregates.

Zöttl S, Kaiser A, Daxner M, Goulart M, Mauracher A, Probst M, Hagelberg F, Denifl S, Scheier P, Echt O - Carbon N Y (2014)

Relative orientation of neighboring C2H4 molecules for the 1 × 1 phase on C60. The angle γ measures the orientation between the two CC axis of two C2H4 molecules, corrected for a tilt due to the curvature. γ is produced by projection of the second CC– axis on the second fullerene face and further projection on the first fullerene face. A detailed definition of γ is given in the text. (A colour version of this figure can be viewed online.)
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4375791&req=5

f0040: Relative orientation of neighboring C2H4 molecules for the 1 × 1 phase on C60. The angle γ measures the orientation between the two CC axis of two C2H4 molecules, corrected for a tilt due to the curvature. γ is produced by projection of the second CC– axis on the second fullerene face and further projection on the first fullerene face. A detailed definition of γ is given in the text. (A colour version of this figure can be viewed online.)
Mentions: The analysis starts with an annealed and optimized C60Et32 aggregate; with a complete first shell and all molecules in hollow sites. The initial structure is heated up 1 K at a time. In each step of the MD simulation an equilibration period of 2 ps is followed by a production run of 2 ps during which the three angles α, β and γ are evaluated. The distributions of α and β versus temperature are displayed in Fig. 7; the distribution of γ in Fig. 8. The color scale of the 2D histograms is chosen so that small occupation numbers (white and dark blue) are visible as well as peaks (yellow and red). Each column, representing an interval of 1 K, is normalized with its total sum and the total maximum of all counts.

Bottom Line: Experimental data also reveal the number of molecules in groove sites of the C60 dimer through tetramer.The identity of the sites, adsorption energies and orientations of the adsorbed molecules are determined by molecular dynamics calculations based on quantum chemical potentials, as well as density functional theory.The decrease in orientational order with increasing temperature is also explored in the simulations whereas in the experiment it is impossible to vary the temperature.

View Article: PubMed Central - PubMed

Affiliation: Institut für Ionenphysik und Angewandte Physik, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.

ABSTRACT

In spite of extensive investigations of ethylene adsorbed on graphite, bundles of nanotubes, and crystals of fullerenes, little is known about the existence of commensurate phases; they have escaped detection in almost all previous work. Here we present a combined experimental and theoretical study of ethylene adsorbed on free C60 and its aggregates. The ion yield of [Formula: see text] measured by mass spectrometry reveals a propensity to form a structurally ordered phase on monomers, dimers and trimers of C60 in which all sterically accessible hollow sites over carbon rings are occupied. Presumably the enhancement of the corrugation by the curvature of the fullerene surface favors this phase which is akin to a hypothetical 1 × 1 phase on graphite. Experimental data also reveal the number of molecules in groove sites of the C60 dimer through tetramer. The identity of the sites, adsorption energies and orientations of the adsorbed molecules are determined by molecular dynamics calculations based on quantum chemical potentials, as well as density functional theory. The decrease in orientational order with increasing temperature is also explored in the simulations whereas in the experiment it is impossible to vary the temperature.

No MeSH data available.


Related in: MedlinePlus