Positronium formation in graphene and graphite
| Autor: | A. J. Fairchild, Alex H. Weiss, M. D. Chrysler, Varghese Anto Chirayath, R. W. Gladen, A. R. Koymen |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Condensed Matter - Mesoscale and Nanoscale Physics Graphene Surface plasmon FOS: Physical sciences 02 engineering and technology Electron Substrate (electronics) 021001 nanoscience & nanotechnology Kinetic energy 01 natural sciences Molecular physics law.invention Positronium Highly oriented pyrolytic graphite law 0103 physical sciences Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Graphite 010306 general physics 0210 nano-technology |
| DOI: | 10.48550/arxiv.1907.10573 |
| Popis: | Positronium (Ps) formation on the surface of clean polycrystalline copper (Cu), highly oriented pyrolytic graphite (HOPG) and multi layer graphene (MLG) grown on a polycrystalline copper substrate has been investigated as a function of incident positron kinetic energy (1.5eV to 1keV). Measurments on Cu indicate that as the kinetic energy of the incident positrons increases from 1.5eV to 900eV, the fraction of positrons that form Ps ($f_{Ps}$) decreases from ~0.5 to ~0.3. However, in HOPG and MLG, instead of a monotonic decrease of $f_{Ps}$ with positron kinetic energy, a sharp peak is observed at ~ 5eV and above ~200eV,remains nearly constant in HOPG and MLG. We propose that in HOPG and MLG, at low incident positron energies the Ps formation is dominated either by a surface Plasmon assisted electron pick up process or by an energy dependent back scattering process. Both these processes can explain the peak observed and the present data can help to augment the understanding of Ps formation from layered materials. Comment: Presented at 18th International Conference on Positron Annihilation, August 19-24, 2018 | Orlando, USA. The following article has been accepted by AIP Conference Proceedings. After it is published, it will be found at https://aip.scitation.org/journal/apc |
| Databáze: | OpenAIRE |
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