  The production of secondary electrons generated by carbon nanoparticles and
pure water medium irradiated by fast protons is studied by means of model
approaches and Monte Carlo simulations. It is demonstrated that due to a
prominent collective response to an external field, the nanoparticles embedded
in the medium enhance the yield of low-energy electrons. The maximal
enhancement is observed for electrons in the energy range where plasmons, which
are excited in the nanoparticles, play the dominant role. Electron yield from a
solid carbon nanoparticle composed of fullerite, a crystalline form of C60
fullerene, is demonstrated to be several times higher than that from liquid
water. Decay of plasmon excitations in carbon-based nanosystems thus represents
a mechanism of increase of the low-energy electron yield, similar to the case
of sensitizing metal nanoparticles. This observation gives a hint for
investigation of novel types of sensitizers to be composed of metallic and
organic parts.
