Methane Adsorption on Graphitic Nanostructures: Every Molecule Counts

Zöttl, Samuel; Kaiser, Alexander; Bartl, Peter; Leidlmair, Christian; Mauracher, Andreas; Probst, Michael; Denifl, Stephan; Echt, Olof; Scheier, P.

doi:10.1021/jz301106x

Cited by 24 publications

(30 citation statements)

References 44 publications

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“…At the same time, curvature increases the distance between atoms adsorbed at hollow sites to an extent that not only helium but even larger particles (including hydrogen, methane, ethylene or nitrogen) can be accommodated in the 1 × 1 phase of C 60 , with one particle each at the centres of the 12 pentagons and 20 hexagons (25 hexagons for C 70 ) [19,22,24,25], for a review see [12]. The anomaly at n = 32 also appeared in mass spectra of C 60 that was allowed to react in a gas aggregation cell with red phosphorous [26] or alkaline earth metals [27].…”

Section: Resultsmentioning

confidence: 99%

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Adsorption of helium on isolated C₆₀and C₇₀anions

et al. 2015

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Adsorption of helium on free, negatively charged fullerenes is studied in this work. Helium nanodroplets have been doped with fullerenes and ionised by electron attachment. For suitable experimental conditions, C − 60 and C − 70 anions are found to be complexed with a large number of helium atoms. Prominent anomalies in the ion abundances indicate the high stability of the commensurate 1 × 1 phase in which all hollow adsorption sites are occupied by one atom each. The adsorption energy for an additional helium atom is about 40% less than for atoms in the commensurate layer, similar to our previous findings for fullerene cations and in agreement with theoretical dissociation energies. Similarly, an anomaly in the adsorption energy occurs when 60 helium atoms are attached to C − 60 or 65 to C − 70 . For C 60 , the anomaly coincides with the one observed for cationic complexes but for C 70 it does not. Implications of these features are discussed in light of several theoretical studies of neutral and positively charged helium-fullerene complexes.

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Section: Resultsmentioning

confidence: 99%

“…However, theoretical studies leave no doubt that 32 helium atoms form a commensurate 1 × 1 phase on neutral or positively charged C 60 [11,13,14]. The same is true for adsorption of methane [24], ethylene [25], and xenon [28] but neither for neon, argon, and krypton [28] nor for polar molecules [29].…”

Section: Resultsmentioning

confidence: 99%

Adsorption of helium on isolated C₆₀and C₇₀anions

et al. 2015

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“…However, an increase in the number of C 60 molecules brings more than just extra surface area: the number and types of interstitial sites 39 between the fullerene molecules also increases.…”

Section: Discussionmentioning

confidence: 99%

Electron ionization of helium droplets containing C₆₀ and alcohol clusters

Goulart

Zappa

Ellis

et al. 2017

Phys. Chem. Chem. Phys.

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aWe report a mass spectrometric investigation of (C 60 ) n clusters mixed with either methanol or ethanol clusters inside helium nanodroplets. The abundance of ion products produced by electron ionization shows marked differences compared with pure methanol/ethanol clusters without C 60 [M. Goulart, P. Bartl, A. Mauracher, F. Zappa, A. M. Ellis and P. Scheier, Phys. Chem. Chem. Phys., 2013, 15, 3577], where clusters containing in excess of a hundred alcohol monomers were observed. In contrast, under identical conditions concerning He droplet size and alcohol pickup pressure, only a small number of alcohol molecules become attached to the fullerene ions. Our results suggest that each fullerene cluster acts as a charge sink, which hampers alcohol cluster formation, as well as intra-cluster ion-molecule reactions. The appearance of specific 'magic number' peaks suggests an enhanced probability for the attachment of small alcohol rings to (C 60 ) n + clusters.

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“…The corresponding anomalies at 32 and 37 have also been observed for complexes of fullerenes with alkaline earth metals, 80 helium, 10 and methane. 81 This interpretation would also provide a rational for the abundance anomalies observed for the odd-numbered series (H 2 ) n HC m z+ at 32 (m = 60) and 37 (m = 70), for z = 1 and 2, because our calculations indicate that the additional lone H atom would be covalently bound atop a carbon atom; it would not block any of the adsorption sites over the hexagons or pentagons that are preferred by the physisorbed H 2 molecules.…”

Section: Abundance Anomalies and Adsorption Of H 2 On Graphitic Sumentioning

confidence: 99%

Adsorption of hydrogen on neutral and charged fullerene: Experiment and theory

Kaiser

Leidlmair

Bartl

et al. 2013

The Journal of Chemical Physics

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A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu The Journal of Chemical Physics 132, 154104 (2010) Helium droplets are doped with fullerenes (either C 60 or C 70 ) and hydrogen (H 2 or D 2 ) and investigated by high-resolution mass spectrometry. In addition to pure helium and hydrogen cluster ions, hydrogen-fullerene complexes are observed upon electron ionization. The composition of the main ion series is (H 2 ) n HC m + where m = 60 or 70. Another series of even-numbered ions, (H 2 ) n C m + , is slightly weaker in stark contrast to pure hydrogen cluster ions for which the even-numbered series (H 2 ) n + is barely detectable. The ion series (H 2 ) n HC m + and (H 2 ) n C m + exhibit abrupt drops in ion abundance at n = 32 for C 60 and 37 for C 70 , indicating formation of an energetically favorable commensurate phase, with each face of the fullerene ion being covered by one adsorbate molecule. However, the first solvation layer is not complete until a total of 49 H 2 are adsorbed on C 60 + ; the corresponding value for C 70 + is 51. Surprisingly, these values do not exhibit a hydrogen-deuterium isotope effect even though the isotope effect for H 2 /D 2 adsorbates on graphite exceeds 6%. We also observe doubly charged fullerene-deuterium clusters; they, too, exhibit abrupt drops in ion abundance at n = 32 and 37 for C 60 and C 70 , respectively. The findings imply that the charge is localized on the fullerene, stabilizing the system against charge separation. Density functional calculations for C 60 -hydrogen complexes with up to five hydrogen atoms provide insight into the experimental findings and the structure of the ions. The binding energy of physisorbed H 2 is 57 meV for H 2 C 60 + and (H 2 ) 2 C 60 + , and slightly above 70 meV for H 2 HC 60 + and (H 2 ) 2 HC 60 + . The lone hydrogen in the odd-numbered complexes is covalently bound atop a carbon atom but a large barrier of 1.69 eV impedes chemisorption of the H 2 molecules. Calculations for neutral and doubly charged complexes are presented as well.

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Methane Adsorption on Graphitic Nanostructures: Every Molecule Counts

Cited by 24 publications

References 44 publications

Adsorption of helium on isolated C₆₀and C₇₀anions

Adsorption of helium on isolated C₆₀and C₇₀anions

Electron ionization of helium droplets containing C₆₀ and alcohol clusters

Adsorption of hydrogen on neutral and charged fullerene: Experiment and theory

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Methane Adsorption on Graphitic Nanostructures: Every Molecule Counts

Cited by 24 publications

References 44 publications

Adsorption of helium on isolated C60and C70anions

Adsorption of helium on isolated C60and C70anions

Electron ionization of helium droplets containing C60 and alcohol clusters

Adsorption of hydrogen on neutral and charged fullerene: Experiment and theory

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Adsorption of helium on isolated C₆₀and C₇₀anions

Adsorption of helium on isolated C₆₀and C₇₀anions

Electron ionization of helium droplets containing C₆₀ and alcohol clusters