Electronic structure and dynamics of optically excited single-wall carbon nanotubes

Abstract

We have studied the electronic structure and charge-carrier dynamics of individual single-wall carbon nanotubes (SWNTs) and nanotube ropes using optical and electron-spectroscopic techniques. The electronic structure of semiconducting SWNTs in the band-gap region is analyzed using near-infrared absorption spectroscopy. A semi-empirical expression for E S 11 transition energies, based on tight-binding calculations is found to give striking agreement with experimental data. Time-resolved PL from dispersed SWNT-micelles shows a decay with a time constant of about 15 ps. Using time-resolved photoemission we also find that the electron-phonon (e-ph) coupling in metallic tubes is characterized by a very small e-ph mass-enhancement of 0.0004. Ultrafast electronelectron scattering of photo-excited carriers in nanotube ropes is finally found to lead to internal thermalization of the electronic system within about 200 fs.

Exciton dynamics probed in carbon nanotube suspensions with narrow diameter distribution

“…The transients discussed in the following section thus have to be seen in the light of relaxation and repopulation dynamics. In contrast, photoluminescence quantum yields and the dynamics of the associated PL decay generally reflect the population dynamics of the photoluminescent state X [14][15][16]. …”

Mechanism of the Far-Infrared Absorption of Carbon-Nanotube Films

“…Transient transmission measurements with various pump-photon energies indicated that roughly half of the absorbed 1.6 eV photons excite the small-gap and metallic NTs [17]. Within 0.2 ps, the excited electrons relax to a Fermi-Dirac distribution f T with electronic temperature T [32]. In the schematic of Fig.…”

Ultrafast Dynamics of Single-Walled Carbon Nanotubes Dispersed in Polymer Films

“…13,14,18,25 These observations have been attributed to a range of dynamic processes including exciton recombination, plasmon relaxation, electron cooling, and radiative relaxation. Differences between isolated [13][14][15][16][17][18] and bundled [17][18][19][20][21][22][23][24] systems could stem from a lack of multitube processes in isolated samples; thus direct comparisons between the two may not be appropriate.…”