Limits...
Decorating (C60) n (+), n = 1-3, with CO2 at low temperatures: Sterically enhanced physisorption.

Mauracher A, Kaiser A, Probst M, Zöttl S, Daxner M, Postler J, Goulart MM, Zappa F, Bohme DK, Scheier P - Int J Mass Spectrom (2013)

Bottom Line: These provide insight into the influence of steric properties on the nature of physisorption.The enhanced stabilities of (C60)2 (+)(CO2)8 and (C60)3 (+)(CO2)1,2 are attributed to physisorption inside the "groove" of the dimer and the two "dimples" in the trimer cations of C60.Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects.

View Article: PubMed Central - PubMed

Affiliation: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.

ABSTRACT

Multiple attachment of CO2 to the monomer, dimer and trimer cations of C60 has been observed in the mass spectra of He nanodroplets sequentially doped with C60 and CO2 and exposed to electron ionization at 50 eV. Remarkable anomalies were seen in the ion yield for CO2 coverage for (C60)2 (+)(CO2)8 and (C60)3 (+)(CO2)1,2. These provide insight into the influence of steric properties on the nature of physisorption. The enhanced stabilities of (C60)2 (+)(CO2)8 and (C60)3 (+)(CO2)1,2 are attributed to physisorption inside the "groove" of the dimer and the two "dimples" in the trimer cations of C60. Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects.

No MeSH data available.


Related in: MedlinePlus

Occupation of the groove sites on a cationic fullerene dimer by 8 CO2 molecules in a fence-like manner (a) and of the dimple sites (one CO2 molecule each) on a trimer (b).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4376293&req=5

fig0015: Occupation of the groove sites on a cationic fullerene dimer by 8 CO2 molecules in a fence-like manner (a) and of the dimple sites (one CO2 molecule each) on a trimer (b).

Mentions: In order to model CO2 molecules in the groove and dimple sites we optimized 8 carbon dioxide molecules in the groove for the dimer (Fig. 3a) and two in the dimples for the trimer (Fig. 3b). Our simulations show the interesting feature that 8 CO2 molecules in the dimer-groove are stable only at low temperatures ∼<60 K. At higher temperatures one or two of them are displaced from the groove. In case of 6 remaining molecules this leads to a highly symmetric ring, similar to what was found for methane in the groove of the C60 dimer [22]. We aim to determine the transition temperature more accurately in extended simulations. Since the interaction between CO2 molecules (64 meV for the CO2 dimer [23]) is larger than the one between methane (22 meV for the CH4 dimer [24]) the mutual orientation of the CO2 molecules is much more strongly influenced by its neighboring adsorbents. The charge distribution on CO2 favors a slipped configuration for the C60 dimer. This could lead to a windmill or fence-like structure (compare Fig. 3a). This is also different from the H2 adsorption on fullerenes, where H2 lies flat against the surface [25].


Decorating (C60) n (+), n = 1-3, with CO2 at low temperatures: Sterically enhanced physisorption.

Mauracher A, Kaiser A, Probst M, Zöttl S, Daxner M, Postler J, Goulart MM, Zappa F, Bohme DK, Scheier P - Int J Mass Spectrom (2013)

Occupation of the groove sites on a cationic fullerene dimer by 8 CO2 molecules in a fence-like manner (a) and of the dimple sites (one CO2 molecule each) on a trimer (b).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376293&req=5

fig0015: Occupation of the groove sites on a cationic fullerene dimer by 8 CO2 molecules in a fence-like manner (a) and of the dimple sites (one CO2 molecule each) on a trimer (b).
Mentions: In order to model CO2 molecules in the groove and dimple sites we optimized 8 carbon dioxide molecules in the groove for the dimer (Fig. 3a) and two in the dimples for the trimer (Fig. 3b). Our simulations show the interesting feature that 8 CO2 molecules in the dimer-groove are stable only at low temperatures ∼<60 K. At higher temperatures one or two of them are displaced from the groove. In case of 6 remaining molecules this leads to a highly symmetric ring, similar to what was found for methane in the groove of the C60 dimer [22]. We aim to determine the transition temperature more accurately in extended simulations. Since the interaction between CO2 molecules (64 meV for the CO2 dimer [23]) is larger than the one between methane (22 meV for the CH4 dimer [24]) the mutual orientation of the CO2 molecules is much more strongly influenced by its neighboring adsorbents. The charge distribution on CO2 favors a slipped configuration for the C60 dimer. This could lead to a windmill or fence-like structure (compare Fig. 3a). This is also different from the H2 adsorption on fullerenes, where H2 lies flat against the surface [25].

Bottom Line: These provide insight into the influence of steric properties on the nature of physisorption.The enhanced stabilities of (C60)2 (+)(CO2)8 and (C60)3 (+)(CO2)1,2 are attributed to physisorption inside the "groove" of the dimer and the two "dimples" in the trimer cations of C60.Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects.

View Article: PubMed Central - PubMed

Affiliation: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens-Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.

ABSTRACT

Multiple attachment of CO2 to the monomer, dimer and trimer cations of C60 has been observed in the mass spectra of He nanodroplets sequentially doped with C60 and CO2 and exposed to electron ionization at 50 eV. Remarkable anomalies were seen in the ion yield for CO2 coverage for (C60)2 (+)(CO2)8 and (C60)3 (+)(CO2)1,2. These provide insight into the influence of steric properties on the nature of physisorption. The enhanced stabilities of (C60)2 (+)(CO2)8 and (C60)3 (+)(CO2)1,2 are attributed to physisorption inside the "groove" of the dimer and the two "dimples" in the trimer cations of C60. Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects.

No MeSH data available.


Related in: MedlinePlus