Research Highlights

Exciton size and mobility in (6,5) carbon nanotubes

L. Lüer, S. Hoseinkhani, D. Polli, J. Crochet, T. Hertel, G. Lanzani, Nature Physics 5, 54 - 58 (2009).

We studied the fundamental properties of excitons (bound electron-hole pairs) in carbon nanotubes. Taking advantage of a highly defined sample and of the high temporal resolution available at Politecnico di Milano, we found that the “exciton size” (electron-hole correlation length) is close to 2 nm, and that the exciton diffusion length in these samples is only on the order of 10 nm. The results are of high importance because i) they validate theoretical descriptions of excitons in carbon nanotubes, that predicted a similar exciton size and ii) they show that many excitons can coexist on an isolated nanotube without the risk of exciton annihilation, making them apt for photonic applications like, lasers and optical switches.

Coherent Phonon Dynamics in Semiconducting Carbon Nanotubes:A Quantitative Study of Electron-Phonon Coupling

L. Lüer, C. Gadermaier, J. Crochet, T. Hertel, D. Brida, G. Lanzani, Phys. Rev. Lett. 102, 127401 (2009).

We excite and detect coherent phonons in semiconducting (6,5) carbon nanotubes via a sub-10-fs pump-probe technique. Simulation of the amplitude and phase profile via time-dependent wave packet theory yields excellent agreement with experimental results under the assumption of molecular excitonic states and allows determining the electron-phonon coupling strength for the two dominant vibrational modes.

Highly conductive molecular junctions based on direct binding of benzene to platinum electrodes.

M. Kiguchi, O. Tal, S. Wohlthat, F. Pauly, M. Krieger, D. Djukic, J.C. Cuevas, J. M. van Ruitenbeek, Phys. Rev. Lett. 101, 046801 (2008). See accompanying Viewpoint Physics 1, 5 (2008).

Juan Carlos Cuevas from Universidad Autonoma de Madrid calculated the properties (geometrical structure, conductance, vibrational energy) of single benzene molecules interfaced with Platinum electrodes via single atomic contacts. The results explained experimental facts obtained by collaborating groups outside of Bimore. The results were selected for a “Viewpoint in Physics”. They are of outstanding importance for two reasons: i) they show that stable contacts between metal electrodes and single molecules can be achieved without the need of a sulphur bridge; this opens our synthetic partners in Denmark and Israel (link!) new possibilities of collaborations with the single molecule conduction groups (IBM and UAM), link!; and ii) they show that the theoretical formalism deployed in Madrid describes correctly the geometrical and electronic structure of single molecules between atomic contacts to metal electrodes.

Full list of publications by the Bimore consortium.

© 2009 Last Modified: January, 2010 Impressum