| Autor: |
Biskupek J; Electron Microscopy of Materials Science, Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany., Skowron ST; School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom., Stoppiello CT; School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom., Rance GA; School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.; Nanoscale and Microscale Research Centre, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom., Alom S; School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom., Fung KLY; School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom., Whitby RJ; School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom., Levitt MH; School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom., Ramasse QM; SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA4 4AD, United Kingdom., Kaiser U; Electron Microscopy of Materials Science, Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, Ulm 89081, Germany., Besley E; School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom., Khlobystov AN; School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom. |
| Abstrakt: |
Molecular motion and bond dissociation are two of the most fundamental phenomena underpinning the properties of molecular materials. We entrapped HF and H 2 O molecules within the fullerene C 60 cage, encapsulated within a single-walled carbon nanotube (X@C 60 )@SWNT, where X = HF or H 2 O. (X@C 60 )@SWNT represents a class of molecular nanomaterial composed of a guest within a molecular host within a nanoscale host, enabling investigations of the interactions of isolated single di- or triatomic molecules with the electron beam. The use of the electron beam simultaneously as a stimulus of chemical reactions in molecules and as a sub-angstrom resolution imaging probe allows investigations of the molecular dynamics and reactivity in real time and at the atomic scale, which are probed directly by chromatic and spherical aberration-corrected high-resolution transmission electron microscopy imaging, or indirectly by vibrational electron energy loss spectroscopy in situ during scanning transmission electron microscopy experiments. Experimental measurements indicate that the electron beam triggers homolytic dissociation of the H-F or H-O bonds, respectively, causing the expulsion of the hydrogen atoms from the fullerene cage, leaving fluorine or oxygen behind. Because of a difference in the mechanisms of penetration through the carbon lattice available for F or O atoms, atomic fluorine inside the fullerene cage appears to be more stable than the atomic oxygen under the same conditions. The use of (X@C 60 )@SWNT, where each molecule X is "packaged" separately from each other, in combination with the electron microscopy methods and density functional theory modeling in this work, enable bond dynamics and reactivity of individual atoms to be probed directly at the single-molecule level. |
