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Nanostructure Characterisation by Electron Beam Techniques
Multi-walled carbon nanotubes irradiated by proton beams:
An energy loss study
Isabel Abril 1,* , Jorge E. Valdés 2 , Rafael Garcia-Molina 3 , Carlos Celedón 2,4 , Rodrigo Segura 5 , Néstor
R. Arista 4 , Patricio Vargas 2
1 Departament de Física Aplicada, Universitat d’Alacant, E-03080 Alacant, Spain
2 Departamento de Física – Laboratorio de Colisiones Atómicas, Universidad Técnica Federico Santa María
(UTFSM), Valparaíso 2390123, Chile
3 Departamento de Física – Centro de Investigación en Óptica y Nanofísica, Universidad de Murcia, E-30100
Murcia, Spain
4 Centro Atómico Bariloche, División Colisiones Atómicas, RA-8400 S. C. de Bariloche, Argentina
5 Departamento de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Chile
*corresponding author ias@ua.es (Isabel Abril)
The irradiation with energetic proton beams impinging normal to the axis of a multiwalled carbon nanotube
(MWCNT) is studied both experimental and theoretically, in the keV energy range. The MWCNTs are
dispersed on top of a very thin film of holey amorphous carbon (a-C) substrate. Measurements of the proton
energy loss distribution at the forward direction are performed by the transmission technique, obtaining energy
loss spectra with two well differentiated peaks.
A semi-classical simulation is employ to elucidate the origin of the peaks in the energy distribution. The
simulation follows the trajectories of each projectile by solving its equation of motion, where the electronic
stopping force was accounted for by a non-linear density functional formalism depending on the local
electronic density.
By the simulation we predict that the experimental low-energy-loss peak is due to protons moving in
quasi-channelling between the most external walls of the MWCNTs. The experimental high-energy-loss peak
are those channelled protons, with larger impact parameter and small angular dispersion after traversing the
a-C film, which can reach the detector at zero angle with only an extra energy loss that shifts to a lower
energy their energy distribution [1].
[1] J. E. Valdés, C. Celedón, R. Segura, I. Abril, R. Garcia-Molina, C. D. Denton, N. R. Arista and P. Vargas,
Carbon 52 (2013)137.
Acknowledgments: This work has been financially supported by the following Grants: Fondecyt 1100759
and USM-DGIP 11.11.11, Financiamiento Basal para Centros Científicos y Tecnológicos de Excelencia
(CEDENNA), the Spanish Ministerio de Economía y Competitividad and the European Regional
Development Fund (Project FIS2010-17225).
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