Ultrafast photoresponse of metallic and semiconducting single-wall carbon nanotubes

Ellingson, Randy J.; Engtrakul, Chaiwat; Jones, Marcus; Samec, Monica; Rumbles, Garry; Nozik, Arthur J.; Heben, Michael J.

doi:10.1103/physrevb.71.115444

Cited by 28 publications

(34 citation statements)

References 45 publications

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“…The magnitude of the peak signals increases linearly with the fluence, as shown in the insets of semiconducting SWNTs. [16][17][18][19][20] This indicates that the photoinduced absorption we observed originates from the excitons in the second energy level. We attribute the short time constant to thermalization of the excitons.…”

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confidence: 70%

“…Photoemission 7 and transient absorption [8][9][10][11][12][13][14][15] transfer of excitons from semiconducting to metallic tubes. When such channels are eliminated in isolated tubes, the energy relaxation can take several picoseconds, [16][17][18][19][20] and exciton lifetimes of several 10 ps 17,18 to several 100 ps 16,19 have been measured. Time-resolved photoluminescence measurements have also shown decay times of several 10 ps.…”

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confidence: 99%

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Exciton diffusion in semiconducting single-walled carbon nanotubes studied by transient absorption microscopy

et al. 2012

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Spatiotemporal dynamics of excitons in isolated semiconducting single-walled carbon nanotubes are studied using transient absorption microscopy. Differential reflection and transmission of an 810-nm probe pulse after excitation by a 750-nm pump pulse are measured. We observe a biexponentially decaying signal with a fast time constant of 0.66 ps and a slower time constant of 2.8 ps. Both constants are independent of the pump fluence. By spatially and temporally resolving the differential reflection, we are able to observe a diffusion of excitons, and measure a diffusion coefficient of 200±10 cm 2 /s at room temperature and 300±10 cm 2 /s at lower temperatures of 10 K and 150 K.

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Exciton diffusion in semiconducting single-walled carbon nanotubes studied by transient absorption microscopy

et al. 2012

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“…2(d) and 2(e) for various pump-probe delays . 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].…”

Section: (D) Figures 2(d) and 2(e)mentioning

confidence: 99%

“…Atomic-force micrographs suggest a NT space-filling fraction F of $0:2. Roughly 2=3 of all NTs are large-gap tubes which become transparent at photon energies below 0.6 eV, whereas the small-gap and metallic NTs can still absorb photons [17].…”

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

et al. 2008

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The far-infrared conductivity of single-wall carbon-nanotube ensembles is dominated by a broad absorption peak around 4 THz whose origin is still debated. We observe an overall depletion of this peak when the nanotubes are excited by a short visible laser pulse. This finding excludes optical absorption due to a particle-plasmon resonance and instead shows that interband transitions in tubes with an energy gap of $10 meV dominate the far-infrared conductivity. A simple model based on an ensemble of two-level systems naturally explains the weak temperature dependence of the far-infrared conductivity by the tubeto-tube variation of the chemical potential.

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“…The spectrum is highly structured, consisting of a series of narrow induced absorption (IA) and induced transmission (IT) peaks, and stands in stark contrast to the broad and nondescript bands exhibited by many complex heterogeneous systems. We first reported this spectrum two years ago, 67,68 and since then, structured spectra have been observed by several other groups, [59][60][61][62]65,66 yet a clear explanation of its origin has not been identified. In this paper, we present evidence that the structured spectrum arises from a nonlinear optical response that causes a photoinduced red-shift in the exciton transition frequency when a second electron-hole pair is excited in the presence of an already existing exciton.…”

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confidence: 99%

Exciton Dynamics and Biexciton Formation in Single-Walled Carbon Nanotubes Studied with Femtosecond Transient Absorption Spectroscopy

et al. 2008

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We used femtosecond transient absorption (TA) spectroscopy to examine the excited state dynamics of singlewalled carbon nanotube (SWNT) bundles embedded in polymer matrices. The SWNTs were excited by a femtosecond pump pulse centered at either 1800, 900, or 550 nm and probed using a white-light continuum extending from 400 to 750 nm. We observed a structured TA spectrum consisting of a series of narrow induced transmission (IT) and induced absorption (IA) bands. The TA spectrum, which is independent of excitation wavelength, appeared on a time scale shorter than our instrument response (200 fs) and persisted for up to 100 ps. TA spectra obtained at a series of pump-probe delay times provided a window through which to monitor the exciton dynamics. We observed three distinct spectral signatures in the time-dependent data: (1) the decay of a broad photobleach, (2) the biphasic decay of narrow IT and IA features, and (3) a dynamical spectral shift of IA bands. These processes were attributed to plasmon relaxation, electron-hole recombination, and lattice relaxation associated with exciton self-trapping, respectively. Analysis of the transient spectrum suggested that it arose from a nonlinear optical response of the SWNT, where excitons produced by the pump pulse modified the transition frequencies of subsequent carrier excitations. The result was a series of IT bands (bleaches) at the ground state absorption frequencies, and associated with each was a corresponding red-shifted absorption band. These induced absorptions were attributed to the formation of biexcitons, fourparticle excitations that are produced through the sequential excitation of two closely spaced electron-hole pairs.

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Ultrafast photoresponse of metallic and semiconducting single-wall carbon nanotubes

Cited by 28 publications

References 45 publications

Exciton diffusion in semiconducting single-walled carbon nanotubes studied by transient absorption microscopy

Exciton diffusion in semiconducting single-walled carbon nanotubes studied by transient absorption microscopy

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

Exciton Dynamics and Biexciton Formation in Single-Walled Carbon Nanotubes Studied with Femtosecond Transient Absorption Spectroscopy

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