book of abstracts - IM2NP

A B S T R A C T S FRIDAY, JULY 2 N A N O S E A 2 0 1 0
electron-electron repulsion is approximated by the simple Yukawa potential. The key-quantity in our study is
the differential cross-
of H0, with the corestate
empty, to a final state with the core-state occupied and an ejected electron of kinetic energy E, within
H0 and V is treated as a small perturbation. The tight-binding (TB) calculational scheme allows to select
only CVV processes in which either the neutralizing or the ejected electrons, in the initial state, lie within
nearest neighbor atomic sites to the core-hole site. Many-body corrections, outside the Fermi's golden rule,
are included in a broadening function B(E) containing: (a) a Lorentian component to cope with lifetime
effects, (b) a Gaussian function to account for the electron-phonon interaction and (c) an asymmetric
broadening function, describing the electron shake-up. The kinetic energy distribution of ejected electrons,
are taken from literature. Measurements of CVV electron emissions from bundles of Single Wall CNTs are
correctly reproduced by averaging N(E) over a statistical mixture of tubes, whose diameters are in the range
of commercial Bucky papers (Fig. 1).
3 – Conclusion.
We used a tight-binding procedure to calculate CVV spectra of electron emitted from ideal CNTs; manybody
electron correlations have been included in a broadening function whose asymmetric component is to
be ascribed to the non negligible role of shake-up electrons. This result has confirmed the validity of the
analysis proposed in Ref.[3], where shake-up effects have been isolated in ion-induced Auger electron
emission from Aluminum and in X-ray photoemission spectra from CNTs .
References
[1] J.J. Lander, Phys. Rev. 91 (1953) 1382; H.D. Hagstrum, Inelastic Ion-Surface Collisions, (Ac.Press, NY, 1977), 1.
[2] C.-O. Almbladh, A. L. Morales, and G. Grossmann, Phys. Rev. B 39 (1989), 3489; C.-O. Almbladh and A. L. Morales, ibid. 39 (1989),
3503; C.-M. Liegener, Phys. Rev. B 43, 7561 (1991); M. Cini, Solid State Commun. 24 (1977), 681; Phys. Rev. B 17 (1978), 2788.
[3] A. Sindona, R.A. Baragiola, G. Falcone, A. Oliva, P. Riccardi, Phys. Rev. A 71, 052903 (2005); A. Sindona, S.A. Rudi, S. Maletta, R.A.
Baragiola, G. Falcone, P. Riccardi, Surf. Sci. 601, 1205 (2007); A. Sindona, F. Plastina, A. Cupolillo, C. Giallombardo, G. Falcone and L. Papagno,
Surf. Sci., 601, 2805 (2007).
[4] G.D. Mahan, Phys. Rev. 163, 612 (1967); P. Nozieres and C.T. De Dominicis, Phys. Rev. 178, 1097 (1969); K. Othaka and Y. Tanabe,
Rev. Mod. Phys. 62, 929 (1990).
[5] E. Perfetto et al., Phys Rev B 76, 233408 (2007).
9H50-10H10
High photoconductivity in carbon nanotube sheets.
V. Grossi, S. Santucci and M. Passacantando (Dipartimento di Fisica, Università degli Studi
dell'Aquila, Via Vetoio 10, I-67100 Coppito (L'Aquila), Italy). valentina.grossi@aquila.infn.it,
sandro.santucci@aquila.infn.it, maurizio.passacantando@aquila.infn.it
1 – Introduction
Photocurrent measurements derived by light excitation have been reported in different configurations
exploiting carbon nanotubes (CNTs) [1]. Photoresponse in macro-bundles of multi-walled carbon nanotubes
(MWCNTs) has been recently observed [2], and a technologically promising high photon-to-current
conversion has been demonstrated for MWCNTs by means of an electrochemical method [3]. Studies on
large area sheets of MWCNTs grown on sapphire substrate [4] using also pulsed laser beams [5] may
provide us opportunities for constructing smart structures with multiple functionalities.
2 – Abstract
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