Browsing by Author "Shyu, FL"

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Electron lifetime in armchair carbon nanotubes
(2004-11-01)
Chiu, CW
;
Shyu, FL
;
Chang, CP
;
Chuu, DS
;
Lin, MF
The excited conduction electrons in metallic armchair carbon nanotubes can decay by inelastic electron-electron scattering. The deexcitation channels include the single-particle and collective excitations of different angular momenta. The higher conduction subbands have more deexcitation channels, or shorter electron lifetimes. Each conduction subband has certain states with very long lifetimes, and a simple relationship between the inverse electron lifetime and the state energy is absent. Such results directly reflect the characteristics of the ID excitation spectra. The inverse electron lifetime contrasts sharply with those of semiconducting carbon nanotubes, graphite, and 2D and 3D metallic systems. Dimensionalities play an important role in the many-body effects. The predicted results could be verified by femtosecond time-resolved optical spectroscopy.
Temperature-dependent carrier dynamics in metallic carbon nanotubes
(2005-10-31)
Chiu, CW
;
Chiu, YH
;
Shyu, FL
;
Chang, CP
;
Chuu, DS
The low energy states in metallic armchair carbon nanotubes can decay by the electron-electron Coulomb interactions with the intraband and the interband excitations. The inelastic scattering rate is very sensitive to the changes in the electronic distribution and the state energy (or the wavevector). The temperature dependence is linear for the Fermi-momentum state. Such dependence is hardly affected by the nanotube radius and the Fermi energy. The electron-electron interactions are more efficient in electronic deexcitations compared with the electron-phonon interactions. The calculated results are roughly consistent with the experimental measurements from the time-resolved photoemission spectroscopy. (c) 2005 Elsevier B.V. All rights reserved.