Migration mechanism of aromatic-edge growth

Graphene layer growth: Collision of migrating five-member rings

“…The initial surface HACA model was based on the armchair edges of aromatics [13], yet more recent work [14][15][16][17][18] has explored growth on zigzag edges, which can be formed by the filling of armchair edge boat sites. A gaseous acetylene molecule can adsorb onto an H-activated zigzag edge (i.e., add to a surface radical formed by H abstraction) and then react to form a fivemembered, cyclopenta edge ring.…”

“…The overall step (1) consists of a series of unimolecular transformations of the chemisorbed C 2 H 2 surface moiety mediated by hydrogen atoms [15,17].…”

“…The previous study [17] undertook a detailed analysis of the migration reaction: energetics were examined at several levels of quantum-chemical theory (DFT, MP2, and PM3), the elementary reaction rates of the migration process were obtained by solving energy transfer master equations (with the MultiWell code [19,20]), and graphene edge growth rates and evolving surface morphologies were obtained in sterically-resolved kinetic Monte Carlo (KMC)…”

“…As one of the consequences of rapid surface migration, the previous authors [17] suggested that two migrating cyclopenta rings could react with one another to form a relatively stable surface species such as ,…”

“…We compare computed reaction rates of the cyclopenta ring "collision" with rates of migration, as migration was one of the dominant steps of the previous kinetic model [17]. We also examine the contribution of desorption of reaction intermediates along the migration pathway.…”