期刊
SMALL
卷 11, 期 5, 页码 622-629出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/smll.201402081
关键词
carbon nanotubes; transmission electron microscopy; single-molecule imaging; organic molecules; electron beam
类别
资金
- EPSRC
- ERC
- Nottingham Nanoscience and Nanotechnology Centre
- New Directions for EPSRC Research Leaders Award
- University of Nottingham
- German Research Foundation (DFG)
- Ministry of Science, Research and Arts (MWK) of the state Baden- Wurttemberg within the Sub-Angstrom Low-Voltage Electron Microscopy project (SALVE)
- EPSRC [EP/L014696/1, EP/G005060/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/L014696/1, EP/G005060/1] Funding Source: researchfish
Structural characterisation of individual molecules by high-resolution transmission electron microscopy (HRTEM) is fundamentally limited by the element and electron energy-specific interactions of the material with the high energy electron beam. Here, the key mechanisms controlling the interactions between the e-beam and C-H bonds, present in all organic molecules, are examined, and the low atomic weight of hydrogenresulting in its facile atomic displacement by the e-beamis identified as the principal cause of the instability of individual organic molecules. It is demonstrated theoretically and proven experimentally that exchanging all hydrogen atoms within molecules with the deuterium isotope, and therefore doubling the atomic weight of the lightest atoms in the structure, leads to a more than two-fold increase in the stability of organic molecules in the e-beam. Substitution of H for D significantly reduces the amount of kinetic energy transferred from the e-beam to the atom (main factor contributing to stability) and also increases the barrier for bond dissociation, primarily due to the changes in the zero-point energy of the C-D vibration (minor factor). The extended lifetime of coronene-d(12), used as a model molecule, enables more precise analysis of the inter-molecular spacing and more accurate measurement of the molecular orientations.
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