Details

Autor(en) / Beteiligte

• Lanzani, G
• Gambetta, A
• Manzoni, C
• Menna, E
• Meneghetti, M
• Cerullo, G
• Tretiak, S
• Piryatinski, A
• Saxena, A
• Martin, R. L
• Bishop, A. R

Titel

Real-time observation of nonlinear coherent phonon dynamics in single-walled carbon nanotubes

Ist Teil von

• Nature physics, 2006-08, Vol.2 (8), p.515-520

Ort / Verlag

London: Nature Publishing Group

Erscheinungsjahr

2006

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Single-walled carbon nanotubes (SWNTs) are π-conjugated, quasi-one-dimensional structures consisting of rolled-up graphene sheets that, depending on their chirality, behave as semiconductors or metals; owing to their unique properties, they enable groundbreaking applications in mechanics, nanoelectronics and photonics. In semiconducting SWNTs, medium-sized excitons (3-5 nm) with large binding energy and oscillator strength are the fundamental excitations; exciton wavefunction localization and one-dimensionality give rise to a strong electron-phonon coupling, the study of which is crucial for the understanding of their electronic and optical properties. Here we report on the use of resonant sub-10-fs visible pulses to generate and detect, in the time domain, coherent phonons in SWNT ensembles. We observe vibrational wavepackets for the radial breathing mode (RBM) and the G mode, and in particular their anharmonic coupling, resulting in a frequency modulation of the G mode by the RBM. Quantum-chemical modelling shows that this effect is due to a corrugation of the SWNT surface on photoexcitation, leading to a coupling between longitudinal and radial vibrations.