  We synthesized monodisperse cobalt-platinum nanoparticles
Co(0.14-0.22)Pt(0.86-0.78) of 9 nm in diameter by colloidal chemistry methods
and deposited them by the Langmuir-Blodgett technique as highly ordered
monolayers onto substrates with e-beam defined gold electrodes. Upon annealing
we observe an increase of conductivity over more than 4 orders of magnitude. A
first attempt of explanation of this unanticipated effect, a nanoparticle
displacement, could not be confirmed for annealing temperatures below 400C. A
second approach, a carbonization of the ligands, however, could be confirmed by
Raman spectroscopy. The simple thermal treatment allows tuning essential
properties of electronic devices based on nanoparticles by the manipulation of
the interparticle coupling, namely the electrical conductivity, the Coulomb
blockade characteristic, and the activation energy of the system.
