Ultrafast dynamics of delocalized and localized electrons in carbon nanotubes.
We report on the dynamics of the dielectric function of single-wall carbon nanotubes in the 10-30 THz frequency range after ultrafast laser excitation. The absence of a distinct free-carrier response is attributed to the photogeneration of strongly bound excitons in the tubes with large energy gaps. We find a feature of enhanced transmission caused by the blocking of optical transitions in small-gap tubes. The rapid decay of a featureless background with pronounced dichroism is associated with the increased absorption of spatially localized charge carriers before thermalization is completed.
Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany.
L
L
Perfetti
T
T
Kampfrath
F
F
Schapper
A
A
Hagen
T
T
Hertel
C M
CM
Aguirre
P
P
Desjardins
R
R
Martel
C
C
Frischkorn
M
M
Wolf