| Autor: |
Stockett, M. H., Gatchell, M., Chen, T., de Ruette, N., Giacomozzi, L., Wolf, M., Schmidt, H. T., Zettergren, H., Cederquist, H. |
| Rok vydání: |
2015 |
| Předmět: |
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| Zdroj: |
J Phys Chem Lett 2015 6 4504 |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1021/acs.jpclett.5b02080 |
| Popis: |
We have measured absolute cross sections for ultrafast (fs) single-carbon knockout from Polycyclic Aromatic Hydrocarbon (PAH) cations as functions of He-PAH center-of-mass collision energy in the range 10-200 eV. Classical Molecular Dynamics (MD) simulations cover this range and extend up to 10$^5$ eV. The shapes of the knockout cross sections are well described by a simple analytical expression yielding experimental and MD threshold energies of $E_{th}^{Exp}=32.5\pm 0.4$ eV and $E_{th}^{MD}=41.0\pm 0.3$ eV, respectively. These are the first measurements of knockout threshold energies for molecules isolated \emph{in vacuo}. We further deduce semi-empirical (SE) and MD displacement energies --- \emph{i.e.} the energy transfers to the PAH molecules at the threshold energies for knockout --- of $T_{disp}^{SE}=23.3\pm 0.3$ eV and $T_{disp}^{MD}=27.0\pm 0.3$ eV. The semi-empirical results compare favorably with measured displacement energies for graphene $T_{disp}=23.6$ eV [Meyer \emph{et al.} Phys. Rev Lett. \textbf{108} 196102 (2012) and \textbf{110} 239902 (2013)]. |
| Databáze: |
arXiv |
| Externí odkaz: |
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