Unusual behavior in magnesium-copper cluster matter produced by helium droplet mediated deposition
| Autor: | Claron J. Ridge, J. M. Boyle, Samuel B. Emery, Yan Xin, Robert J. Buszek, C M Lindsay, Jerry A. Boatz, Brian K. Little |
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| Rok vydání: | 2015 |
| Předmět: |
Magnesium
Inorganic chemistry Condensation General Physics and Astronomy chemistry.chemical_element Dark field microscopy Copper Nanoclusters chemistry Chemical engineering Transmission electron microscopy Scanning transmission electron microscopy Deposition (phase transition) Physical and Theoretical Chemistry |
| Zdroj: | The Journal of chemical physics. 142(8) |
| ISSN: | 1089-7690 |
| Popis: | We demonstrate the ability to produce core-shell nanoclusters of materials that typically undergo intermetallic reactions using helium droplet mediated deposition. Composite structures of magnesium and copper were produced by sequential condensation of metal vapors inside the 0.4 K helium droplet baths and then gently deposited onto a substrate for analysis. Upon deposition, the individual clusters, with diameters ∼5 nm, form a cluster material which was subsequently characterized using scanning and transmission electron microscopies. Results of this analysis reveal the following about the deposited cluster material: it is in the un-alloyed chemical state, it maintains a stable core-shell 5 nm structure at sub-monolayer quantities, and it aggregates into unreacted structures of ∼75 nm during further deposition. Surprisingly, high angle annular dark field scanning transmission electron microscopy images revealed that the copper appears to displace the magnesium at the core of the composite cluster despite magnesium being the initially condensed species within the droplet. This phenomenon was studied further using preliminary density functional theory which revealed that copper atoms, when added sequentially to magnesium clusters, penetrate into the magnesium cores. |
| Databáze: | OpenAIRE |
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