Catalyzing Bond‐Dissociation in Graphene via Alkali‐Iodide Molecules

Abstract

SAC has played a vital role in electronbeam-assisted defect-formation reactions in 2D-materials decorated with atomic species. [2] The reported defect structures, such as, vacancies, holes, and nanoribbons, have promising applications such as molecular sieving, [3,4] confinement, [5] magnetism, [6] electrochemistry, [7] and for DNA translocation sensors. [8] SAC was shown to be triggered by transition-metal atoms and silicon, [9][10][11] which form covalent bonds with the underlying graphene and thus lead to some charge redistribution. [11] This weakens the CC atom bonding in the graphene lattice and facilitates vacancy formation in the graphene lattice under high-energy electron irradiation. The dangling bonds at the vacancy site have the tendency to attract other SAC atoms due to their high reactivity compared to pristine graphene, [12] hence, resulting in additional vacancy formation ultimately leading to the formation of holes. [13][14][15][16] Experimental studies highlight that group-I (alkali), group-III, and group-VIII (noble gas) atoms do not show SAC; instead, group-I atomic species form pure ionic bonds, and group-III atoms form partial ionic and covalent bonds with graphene. [17,18] However, the CC bond-weakening reaction in single-layer graphene (SLG) has not been studied in case of molecular species. Of particular interest are Atomic design of a 2D-material such as graphene can be substantially influenced by etching, deliberately induced in a transmission electron microscope. It is achieved primarily by overcoming the threshold energy for defect formation by controlling the kinetic energy and current density of the fast electrons.Recent studies have demonstrated that the presence of certain species of atoms can catalyze atomic bond dissociation processes under the electron beam by reducing their threshold energy. Most of the reported catalytic atom species are single atoms, which have strong interaction with single-layer graphene (SLG). Yet, no such behavior has been reported for molecular species. This work shows by experimentally comparing the interaction of alkali and halide species separately and conjointly with SLG, that in the presence of electron irradiation, etching of SLG is drastically enhanced by the simultaneous presence of alkali and iodine atoms. Density functional theory and first principles molecular dynamics calculations reveal that due to chargetransfer phenomena the CC bonds weaken close to the alkali-iodide species, which increases the carbon displacement cross-section. This study ascribes pronounced etching activity observed in SLG to the catalytic behavior of the alkali-iodide species in the presence of electron irradiation.

A Preparative Mass Spectrometer to Deposit Intact Large Native Protein Complexes

“…Electrospray ion beam deposition (ES-IBD) is a preparative mass spectrometry , technique, capable of producing highly purified molecular samples for single molecule imaging. It is routinely used for SPM with smaller (bio)­molecules ,− and has been demonstrated also for TEM, − LEEH, , and recently cryo-EM. , In contrast to organic molecular beam epitaxy (OMBE), , ES-IBD is not limited to small and volatile molecules. In ES-IBD, molecules are ionized in an electrospray ion source, transferred into the gas phase, and mass-analyzed in a vacuum.…”

A preparative mass spectrometer to deposit intact large native protein complexes

“…[12][13][14][15] Electrospray ion beam deposition (ES-IBD) is a preparative mass spectrometry 16,17 technique, capable of producing highly purified molecular samples for single molecule imaging. It is routinely used for SPM with smaller (bio)molecules 5,[18][19][20][21][22][23][24] and has been demonstrated also for TEM, [25][26][27][28] LEEH, 2,9 and recently cryo-EM. 29,30 In contrast to organic molecular beam epitaxy (OMBE), 31,32 ES-IBD is not limited to small and volatile molecules.…”