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V Encuentro Sud Americano de Colisiones Inelásticas en la Materia
Plasmon excitation in single walled carbon nanotubes by charged particles
S. Segui 1 , D. J. Mowbray 2 , 3 , J. L. Gervasoni 1 , Z. L. Mišković 2 and N. R. Arista 1
1
Centro Atómico Bariloche (CNEA) 8400 S.C. de Bariloche, Río Negro, Argentina
2
Department of Applied Mathematics, Univ. of Waterloo, Waterloo, Ontario, Canada
3
Nano-Bio Spectroscopy Group, Depto. Física de Materiales, Univ. País Vasco, San Sebastián, Spain
email address corresponding author: segui@cab.cnea.gov.ar
The excitation of plasmons in singleand
multi-walled nanotubes has been the
object of several experimental and theoretical
studies in recent years, since it plays an
important role in a variety of interesting
phenomena, such as probing the nanotube
response by EELS, formation of electron
image states, etc.
Due to the geometry of single-walled
nanotubes, and the characteristics of the
electronic structure of carbonaceous
nanostructures (with σ and π orbitals), the
excitation of plasmons is conveniently
described by a two-fluids formulation of the
hydrodynamic model. In this formulation, σ
and π electrons are treated as separate twodimensional
fluids constrained to the same
cylindrical surface. The electrostatic
interaction between the fluids gives rise to
splitting of the plasmon frequencies into two
groups of distinct energies.
In this work we present a quantization
of the two-fluids hydrodynamic model [1].
This procedure allows us to obtain the
average number of plasmons excited by a fast
charged particle impinging on the nanotube at
different positions. We also calculate several
other quantities, such as the stopping power,
energy loss spectra and total energy loss,
which could be compared with experimental
measurements. We study the effect of various
parameters, such as the velocity of the
incident particle, the impact parameter, the
inclination of the trajectory with respect to
the tube’s axis, etc. Figure 1 shows the total
energy loss suffered by a proton passing near
a 7 Å radius nanotube, as a function of the
incident velocity v, for (a) perpendicular and
(b) oblique trajectory, and different minimum
distances from the tube's axis.
Figure 1. Total energy loss E l o s s versus
speed v for proton trajectory passing near
a SWCNT of radius R=7 Å with an angle
relative to the tube's axis of (a) 90° and
(b) 45°, at the minimum separation of r m i n
= 7.5 Å (top), 8.0, 8.5, 9.0, 9.5, 10.0, and
10.5 Å (bottom).
References
[1] D. J. Mowbray, S. Segui, J. L. Gervasoni, Z.
L. Mišković and N. R. Arista, Phys. Rev. B. 82,
035405 (2010).
49 Valparaíso, Chile