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Adsorbate-induced curvature and stiffening of graphene.

Svatek SA, Scott OR, Rivett JP, Wright K, Baldoni M, Bichoutskaia E, Taniguchi T, Watanabe K, Marsden AJ, Wilson NR, Beton PH - Nano Lett. (2014)

Bottom Line: This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene.The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride.Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Nottingham , Nottingham NG7 2RD, United Kingdom.

ABSTRACT
The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

No MeSH data available.


Related in: MedlinePlus

(a) Schematic of n-alkane adsorbed on G. The −CH2–group at s = 0 is positioned at the preferred adsorptionsite. Due to the mismatch in separation of carbon atoms in the chainand the graphene, the −CH2– groups along s are offset relative to their preferred adsorption siteby an amount Δl (≈ (s/a)δa). (b) Schematic sideview of the adsorption; in the flat configuration, the differencein periods leads to a variation in local registry. The variation ofregistry can be modified if the TTC/G surface is curved, and completelyeliminated if the ratios of the arc lengths (periods) is equal tothe ratio of radii of curvature, that is, (a + δa)/a = (R + h)/R, or R = Rc = ha/δa. (c)In-phase (blue) and out-of-phase (red) curvature dependent moirévariation of adsorption energy with respect to a surface with a radiusof curvature R. (d) Bending energy of the adsorbedTTC versus inverse radius of curvature. (e) Adsorption energy of TTCon graphene (solid line) and numerical calculations (blue dots) fora curved graphene surface, indicating that the curvature-related moiréeffect successfully accounts for the calculated behavior.
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fig3: (a) Schematic of n-alkane adsorbed on G. The −CH2–group at s = 0 is positioned at the preferred adsorptionsite. Due to the mismatch in separation of carbon atoms in the chainand the graphene, the −CH2– groups along s are offset relative to their preferred adsorption siteby an amount Δl (≈ (s/a)δa). (b) Schematic sideview of the adsorption; in the flat configuration, the differencein periods leads to a variation in local registry. The variation ofregistry can be modified if the TTC/G surface is curved, and completelyeliminated if the ratios of the arc lengths (periods) is equal tothe ratio of radii of curvature, that is, (a + δa)/a = (R + h)/R, or R = Rc = ha/δa. (c)In-phase (blue) and out-of-phase (red) curvature dependent moirévariation of adsorption energy with respect to a surface with a radiusof curvature R. (d) Bending energy of the adsorbedTTC versus inverse radius of curvature. (e) Adsorption energy of TTCon graphene (solid line) and numerical calculations (blue dots) fora curved graphene surface, indicating that the curvature-related moiréeffect successfully accounts for the calculated behavior.

Mentions: The elements of the model are shown schematicallyin Figure 3a. The lowest energy adsorptionsite for each −CH2– group is in alignmentwith the center of a hexagon in the underlying graphene (s = 0 in the schematic in Figure 3a). At position s along the alkane chain a given group is displaced outof registry by Δl (= sδa/a to first order in δa).However, if we introduce curvature, the relative displacement maybe reduced (see Figure 3b) due to the differencein radius of curvature of the graphene, R, and theadsorbed molecule, R + h, where h is the separation of the alkane and graphene. Indeed, the preferredregistry can be completely restored if (a + δa)/a = (R + h)/R (Figure 3b).This is satisfied at a critical radius of curvature, Rc = ah/δa = hRm/a, where Rm is a moiré length (= a2/δa) associated with the mismatch betweenthe alkane and graphene repeat lengths.


Adsorbate-induced curvature and stiffening of graphene.

Svatek SA, Scott OR, Rivett JP, Wright K, Baldoni M, Bichoutskaia E, Taniguchi T, Watanabe K, Marsden AJ, Wilson NR, Beton PH - Nano Lett. (2014)

(a) Schematic of n-alkane adsorbed on G. The −CH2–group at s = 0 is positioned at the preferred adsorptionsite. Due to the mismatch in separation of carbon atoms in the chainand the graphene, the −CH2– groups along s are offset relative to their preferred adsorption siteby an amount Δl (≈ (s/a)δa). (b) Schematic sideview of the adsorption; in the flat configuration, the differencein periods leads to a variation in local registry. The variation ofregistry can be modified if the TTC/G surface is curved, and completelyeliminated if the ratios of the arc lengths (periods) is equal tothe ratio of radii of curvature, that is, (a + δa)/a = (R + h)/R, or R = Rc = ha/δa. (c)In-phase (blue) and out-of-phase (red) curvature dependent moirévariation of adsorption energy with respect to a surface with a radiusof curvature R. (d) Bending energy of the adsorbedTTC versus inverse radius of curvature. (e) Adsorption energy of TTCon graphene (solid line) and numerical calculations (blue dots) fora curved graphene surface, indicating that the curvature-related moiréeffect successfully accounts for the calculated behavior.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4326047&req=5

fig3: (a) Schematic of n-alkane adsorbed on G. The −CH2–group at s = 0 is positioned at the preferred adsorptionsite. Due to the mismatch in separation of carbon atoms in the chainand the graphene, the −CH2– groups along s are offset relative to their preferred adsorption siteby an amount Δl (≈ (s/a)δa). (b) Schematic sideview of the adsorption; in the flat configuration, the differencein periods leads to a variation in local registry. The variation ofregistry can be modified if the TTC/G surface is curved, and completelyeliminated if the ratios of the arc lengths (periods) is equal tothe ratio of radii of curvature, that is, (a + δa)/a = (R + h)/R, or R = Rc = ha/δa. (c)In-phase (blue) and out-of-phase (red) curvature dependent moirévariation of adsorption energy with respect to a surface with a radiusof curvature R. (d) Bending energy of the adsorbedTTC versus inverse radius of curvature. (e) Adsorption energy of TTCon graphene (solid line) and numerical calculations (blue dots) fora curved graphene surface, indicating that the curvature-related moiréeffect successfully accounts for the calculated behavior.
Mentions: The elements of the model are shown schematicallyin Figure 3a. The lowest energy adsorptionsite for each −CH2– group is in alignmentwith the center of a hexagon in the underlying graphene (s = 0 in the schematic in Figure 3a). At position s along the alkane chain a given group is displaced outof registry by Δl (= sδa/a to first order in δa).However, if we introduce curvature, the relative displacement maybe reduced (see Figure 3b) due to the differencein radius of curvature of the graphene, R, and theadsorbed molecule, R + h, where h is the separation of the alkane and graphene. Indeed, the preferredregistry can be completely restored if (a + δa)/a = (R + h)/R (Figure 3b).This is satisfied at a critical radius of curvature, Rc = ah/δa = hRm/a, where Rm is a moiré length (= a2/δa) associated with the mismatch betweenthe alkane and graphene repeat lengths.

Bottom Line: This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene.The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride.Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Nottingham , Nottingham NG7 2RD, United Kingdom.

ABSTRACT
The adsorption of the alkane tetratetracontane (TTC, C44H90) on graphene induces the formation of a curved surface stabilized by a gain in adsorption energy. This effect arises from a curvature-dependent variation of a moiré pattern due to the mismatch of the carbon-carbon separation in the adsorbed molecule and the period of graphene. The effect is observed when graphene is transferred onto a deformable substrate, which in our case is the interface between water layers adsorbed on mica and an organic solvent, but is not observed on more rigid substrates such as boron nitride. Our results show that molecular adsorption can be influenced by substrate curvature, provide an example of two-dimensional molecular self-assembly on a soft, responsive interface, and demonstrate that the mechanical properties of graphene may be modified by molecular adsorption, which is of relevance to nanomechanical systems, electronics, and membrane technology.

No MeSH data available.


Related in: MedlinePlus