Energy loss of protons in carbon nanotubes: Experiments and calculations |
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Authors: | I Kyriakou C Celedón R Segura D Emfietzoglou P Vargas JE Valdés I Abril CD Denton K Kostarelos R Garcia-Molina |
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Affiliation: | 1. Medical Physics Lab., University of Ioannina, Ioannina 451 10, Greece;2. Atomic Collisions Laboratory, Physics Department, UTFSM, Valparaíso 2390123, Chile;3. Centro de Nanociencia de Valparaíso, UTFSM, Valparaíso 2390123, Chile;4. Departamento de Química y Bioquímica, Universidad de Valparaíso, Chile;5. Departament de Física Aplicada, Universitat d’Alacant, Apartat 99, E-03080 Alacant, Spain;6. Nanomedicine Lab., University of London, London WC1N 1AX, UK;7. Departamento de Física – CIOyN, Universidad de Murcia, Apartado 4021, E-30080 Murcia, Spain |
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Abstract: | We have studied the energy loss of protons in multi-walled carbon nanotube (MWCNT) samples, both experimentally and theoretically. The experiments were done in transmission geometry, using 6 and 10 keV proton beams, with the MWCNT targets dispersed on top of a ~20 nm-thick holey carbon coated TEM grid (amorphous carbon film, a-C). The energy loss of protons interacting with the MWCNTs and the amorphous carbon film is obtained after analyzing the signals coming from both types of carbon allotropes. The electronic energy loss of protons is calculated using the dielectric formalism, with the target energy loss function built from optical data. Comparison of experimental and theoretical data indicates that model calculations appropriate for three-dimensional (bulk) targets substantially overestimate the energy loss to MWCNTs. In contrast, a recent parameterization of the dielectric function of MWCNTs predicts significantly lower stopping power values compared to the bulk models, which is more in line with the present experimental data when considering the additional stopping mechanisms that are effective in the keV range. |
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