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Home List of Titles Chemical structural effects on gamma-ray spectra of positron annihilation in fluorobenzenes
Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/226373
- Chemical structural effects on gamma-ray spectra of positron annihilation in fluorobenzenes
- Wang, Feng; Ma, X. G.; Selvam, L.; Gribakin, G. F.; Surko, C. M.
- Spectra of gamma-ray Doppler shifts for positron annihilation in benzene and its fluoro-derivatives are simulated using low energy plane wave positron (LEPWP) approximation. The results are compared with available measurements. It is found that the Doppler shifts in these larger aromatic compounds are dominated by the contributions of the valence electrons and that the LEPWP model overestimates the measurements by approximately 30%, in agreement with previous findings in noble gases and small molecules. It is further revealed that the halogen atoms not only switch the sign of the charges on carbon atoms that they bond to, but that they also polarize other C-H bonds in the molecule leading to a redistribution of the molecular electrostatic potentials. As a result, it is likely that the halogen atoms contribute more significantly to the annihilation process. The present study also suggests that, while the Doppler shifts are sensitive to the number of valence electrons in the molecules, they are less sensitive to the chemical structures of isomers that have the same numbers and type of atoms and, hence, the same numbers of electrons. Further investigation of this effect is warranted.
- Publication type
- Journal article
- Research centre
- Swinburne University of Technology. Faculty of Life and Social Sciences
- European Physical Journal D, Vol. 66, no. 4 (Apr 2012), article no. 107
- Publication year
- FOR Code(s)
- 02 Physical Sciences
- Chemical structures; Fluorobenzenes; Gamma-ray Doppler shifts; Spectra; Positron annihilation
- Publisher URL
- Copyright © EDP Sciences, Societa Italiana di Fisica, Springer-Verlag 2012.
- Additional information
- The authors acknowledge support from the Australia Research Council (ARC) under the Discovery Project (DP) scheme, the National Computational Infrastructure (NCI) at the Australian National University (ANU) under the Merit Allocation Scheme and a Swinburne University Postgraduate Research Award (SUPRA).
- Peer reviewed