Ultrafast spectroscopy of midinfrared internal exciton transitions in separated single-walled carbon nanotubes.
We report a femtosecond midinfrared study of the broadband low-energy response of individually separated (6,5) and (7,5) single-walled carbon nanotubes. Strong photoinduced absorption is observed around 200 meV, whose transition energy, oscillator strength, resonant chirality enhancement, and dynamics manifest the observation of quasi-one-dimensional intraexcitonic transitions. A model of the nanotube 1s-2p cross section agrees well with the signal amplitudes. Our study further reveals saturation of the photoinduced absorption with increasing phase-space filling of the correlated e-h pairs.
Wang
Jigang
J
Materials Sciences Division, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Graham
Matt W
MW
Ma
Yingzhong
Y
Fleming
Graham R
GR
Kaindl
Robert A
RA