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Single adatom dynamics at monatomic steps of free-standing few-layer reduced graphene.

Chang H, Saito M, Nagai T, Liang Y, Kawazoe Y, Wang Z, Wu H, Kimoto K, Ikuhara Y - Sci Rep (2014)

Bottom Line: Steps and their associated adatoms extensively exist and play prominent roles in affecting surface properties of materials.Single adatom prefers to stay at the edges of the atomic steps of few-layer reduced graphene and evolve with the steps.Such single adatoms at monatomic steps and ultrasmall atomic steps open up a new window for surface physics and chemistry for graphene-based as well as other two-dimensional materials.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Material Processing and Die &Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.

ABSTRACT
Steps and their associated adatoms extensively exist and play prominent roles in affecting surface properties of materials. Such impacts should be especially pronounced in two-dimensional, atomically-thin membranes like graphene. However, how single adatom behaves at monatomic steps of few-layer graphene is still illusive. Here, we report dynamics of individual adatom at monatomic steps of free-standing few-layer reduced graphene under the electron beam radiations, and demonstrate the prevalent existence of monatomic steps even down to unexpectedly ultrasmall lateral size of a circular diameter of ~5 Å. Single adatom prefers to stay at the edges of the atomic steps of few-layer reduced graphene and evolve with the steps. Moreover, we also find that how the single adatom behaves at atomic step edges can be remarkably influenced by the type of adatoms and step edges. Such single adatoms at monatomic steps and ultrasmall atomic steps open up a new window for surface physics and chemistry for graphene-based as well as other two-dimensional materials.

No MeSH data available.


Dynamics of single adatoms and monatomic steps with ultrasmall lateral size on the free-standing few-layer reduced graphene.(a–f), Snapshot of HAADF STEM images at different time: 3 s (a), 54 s (b), 126 s (c), 177 s (d), 222 s (e) and 252 s (f). The atomic steps are indicated by white arrows. Each image is produced from the overlapping of 10 continuous snapshots and low-pass filtered. (g–i), Snapshot of HAADF STEM images at different time: 3 s (g), 123 s (h), and 300 s (i). Each image is low-pass filtered. Individual adatoms are highlighted by white arrows. Scale bars, 1 nm. The dynamics is also shown in Supplementary Movies S1 and S2.
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f2: Dynamics of single adatoms and monatomic steps with ultrasmall lateral size on the free-standing few-layer reduced graphene.(a–f), Snapshot of HAADF STEM images at different time: 3 s (a), 54 s (b), 126 s (c), 177 s (d), 222 s (e) and 252 s (f). The atomic steps are indicated by white arrows. Each image is produced from the overlapping of 10 continuous snapshots and low-pass filtered. (g–i), Snapshot of HAADF STEM images at different time: 3 s (g), 123 s (h), and 300 s (i). Each image is low-pass filtered. Individual adatoms are highlighted by white arrows. Scale bars, 1 nm. The dynamics is also shown in Supplementary Movies S1 and S2.

Mentions: To shed light on the dynamics of both ultrasmall monatomic steps and adatoms at the step edges under electron beam radiations, we present HAADF STEM images of the dynamics of a monatomic step edge with adatoms (Fig. 2a–f and Supplementary Movie S1). The atomic step edge (edge 2) first combines with another atomic step edge below (edge 3) (Fig. 2a–c). At different time, one atomic step edge in the left (edge 1) joins the previously combined step edges (Fig. 2d–f). Figure 2a–f shows the adatoms, which are identified as sodium (Na) atoms by x-ray photoelectron spectra (XPS) together with the HAADF intensity analysis from experimental and simulated HAADF STEM images (Fig. 3 and Supplementary Figs. S5 and S6)33. The sodium adatoms at the edges show a high mobility at the edges and always move along the edges (Fig. 2a–f and Supplementary Movie S1). Moreover, we also show dynamics of another ultrasmall monatomic step edge with few adatoms at edges in Supplementary Fig. S7. Despite of their similar lateral size, the atomic step edges in Supplementary Fig. S7 show different behaviors from the step edges in Fig. 2a–f, and are much more stable with their shapes changed only slightly during the observation. Although there are other step edges of ultrasmall lateral size near atomic step edges, no combination takes place in the whole imaging process (Supplementary Fig. S7). These differences may result from the local strain in the step area, from the adatoms at the step edges and from the step edge structures.


Single adatom dynamics at monatomic steps of free-standing few-layer reduced graphene.

Chang H, Saito M, Nagai T, Liang Y, Kawazoe Y, Wang Z, Wu H, Kimoto K, Ikuhara Y - Sci Rep (2014)

Dynamics of single adatoms and monatomic steps with ultrasmall lateral size on the free-standing few-layer reduced graphene.(a–f), Snapshot of HAADF STEM images at different time: 3 s (a), 54 s (b), 126 s (c), 177 s (d), 222 s (e) and 252 s (f). The atomic steps are indicated by white arrows. Each image is produced from the overlapping of 10 continuous snapshots and low-pass filtered. (g–i), Snapshot of HAADF STEM images at different time: 3 s (g), 123 s (h), and 300 s (i). Each image is low-pass filtered. Individual adatoms are highlighted by white arrows. Scale bars, 1 nm. The dynamics is also shown in Supplementary Movies S1 and S2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129415&req=5

f2: Dynamics of single adatoms and monatomic steps with ultrasmall lateral size on the free-standing few-layer reduced graphene.(a–f), Snapshot of HAADF STEM images at different time: 3 s (a), 54 s (b), 126 s (c), 177 s (d), 222 s (e) and 252 s (f). The atomic steps are indicated by white arrows. Each image is produced from the overlapping of 10 continuous snapshots and low-pass filtered. (g–i), Snapshot of HAADF STEM images at different time: 3 s (g), 123 s (h), and 300 s (i). Each image is low-pass filtered. Individual adatoms are highlighted by white arrows. Scale bars, 1 nm. The dynamics is also shown in Supplementary Movies S1 and S2.
Mentions: To shed light on the dynamics of both ultrasmall monatomic steps and adatoms at the step edges under electron beam radiations, we present HAADF STEM images of the dynamics of a monatomic step edge with adatoms (Fig. 2a–f and Supplementary Movie S1). The atomic step edge (edge 2) first combines with another atomic step edge below (edge 3) (Fig. 2a–c). At different time, one atomic step edge in the left (edge 1) joins the previously combined step edges (Fig. 2d–f). Figure 2a–f shows the adatoms, which are identified as sodium (Na) atoms by x-ray photoelectron spectra (XPS) together with the HAADF intensity analysis from experimental and simulated HAADF STEM images (Fig. 3 and Supplementary Figs. S5 and S6)33. The sodium adatoms at the edges show a high mobility at the edges and always move along the edges (Fig. 2a–f and Supplementary Movie S1). Moreover, we also show dynamics of another ultrasmall monatomic step edge with few adatoms at edges in Supplementary Fig. S7. Despite of their similar lateral size, the atomic step edges in Supplementary Fig. S7 show different behaviors from the step edges in Fig. 2a–f, and are much more stable with their shapes changed only slightly during the observation. Although there are other step edges of ultrasmall lateral size near atomic step edges, no combination takes place in the whole imaging process (Supplementary Fig. S7). These differences may result from the local strain in the step area, from the adatoms at the step edges and from the step edge structures.

Bottom Line: Steps and their associated adatoms extensively exist and play prominent roles in affecting surface properties of materials.Single adatom prefers to stay at the edges of the atomic steps of few-layer reduced graphene and evolve with the steps.Such single adatoms at monatomic steps and ultrasmall atomic steps open up a new window for surface physics and chemistry for graphene-based as well as other two-dimensional materials.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Material Processing and Die &Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China.

ABSTRACT
Steps and their associated adatoms extensively exist and play prominent roles in affecting surface properties of materials. Such impacts should be especially pronounced in two-dimensional, atomically-thin membranes like graphene. However, how single adatom behaves at monatomic steps of few-layer graphene is still illusive. Here, we report dynamics of individual adatom at monatomic steps of free-standing few-layer reduced graphene under the electron beam radiations, and demonstrate the prevalent existence of monatomic steps even down to unexpectedly ultrasmall lateral size of a circular diameter of ~5 Å. Single adatom prefers to stay at the edges of the atomic steps of few-layer reduced graphene and evolve with the steps. Moreover, we also find that how the single adatom behaves at atomic step edges can be remarkably influenced by the type of adatoms and step edges. Such single adatoms at monatomic steps and ultrasmall atomic steps open up a new window for surface physics and chemistry for graphene-based as well as other two-dimensional materials.

No MeSH data available.