Pump-Probe Spectroscopy of Exciton Dynamics in (6,5) Carbon Nanotubes

Zhu, Zipeng; Crochet, Jared; Wang, Jialiang; Hersam, Mark C.; Ulbricht, Hendrik; Resasco, Daniel E.; Hertel, Tobias

doi:10.1021/jp0669411

Cited by 115 publications

(187 citation statements)

References 32 publications

(62 reference statements)

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“…Each of the transitions in the absorption spectrum creates a pair of diagonal peaks in the 2D-WL spectrum. The negative peak exactly on the diagonal (blue) corresponds to photobleaching of the direct bandgap transition, while the blue-shifted positive peak along the probe axis is from an excited state absorption (red) 12,19 . In addition to the diagonal peaks, cross peaks appear that correlate different chirality tubes.…”

Section: Resultsmentioning

confidence: 99%

“…Instead, these cross peaks are measuring the electronic correlation internal to the nanotubes. In other words, they arise because the S 1 and S 2 electronic states are not perfectly orthogonal 19 . The centre line slopes are negative and elongated perpendicular to the diagonal (the dashed line is a visual guide), which indicates that the S 1 and S 2 transitions are anti-correlated.…”

Section: Article Nature Communications | Doi: 101038/ncomms7732mentioning

confidence: 99%

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Energy transfer pathways in semiconducting carbon nanotubes revealed using two-dimensional white-light spectroscopy

et al. 2015

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Thin film networks of highly purified semiconducting carbon nanotubes (CNTs) are being explored for energy harvesting and optoelectronic devices because of their exceptional transport and optical properties. The nanotubes in these films are in close contact, which permits energy to flow through the films, although the pathways and mechanisms for energy transfer are largely unknown. Here we use a broadband continuum to collect femtosecond two-dimensional white-light spectra. The continuum spans 500 to 1,300 nm, resolving energy transfer between all combinations of bandgap (S 1 ) and higher (S 2 ) transitions. We observe ultrafast energy redistribution on the S 2 states, non-Förster energy transfer on the S 1 states and anti-correlated energy levels. The two-dimensional spectra reveal competing pathways for energy transfer, with S 2 excitons taking routes depending on the bandgap separation, whereas S 1 excitons relax independent of the bandgap. These observations provide a basis for understanding and ultimately controlling the photophysics of energy flow in CNT-based devices.

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Section: Resultsmentioning

confidence: 99%

Section: Article Nature Communications | Doi: 101038/ncomms7732mentioning

confidence: 99%

Energy transfer pathways in semiconducting carbon nanotubes revealed using two-dimensional white-light spectroscopy

et al. 2015

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“…To date, a large number of ensemble studies using pump-probe and time-resolved photoluminescence ͑PL͒ spectroscopy exist, reporting on mono-or multiexponential relaxation dynamics with decay times ranging from few to several tens of picoseconds for different sample materials. 4,6,7 Temperature dependent PL measurements suggest that the excited state relaxation reflects a complex interplay between excitonic states of different parity that are optically bright or dark depending on their accessibility from the ground state. 8,9 At present, excited state lifetimes are thought to be limited by fast transitions to these dark states but also by quenching related to defect related trap states.…”

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confidence: 99%

“…Remarkably, this value agrees very well with the 6 ps determined by pump-probe measurements for the same CoMoCat nanotube material allowing for a direct comparison of the results achieved by both techniques. 6 On the other hand, ensemble measurements need to result in multiexponential decay profiles in which fitted lifetimes will reflect summation over decay times with different contributions. Extremely long lifetimes in the range of nanoseconds as reported in the literature have not been observed in our single nanotube measurements.…”

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Exciton decay dynamics in individual carbon nanotubes at room temperature

Gokus

Hartschuh

Harutyunyan

et al. 2008

Applied Physics Letters

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We studied the exciton decay dynamics of individual semiconducting single-walled carbon nanotubes at room temperature using time-resolved photoluminescence spectroscopy. The photoluminescence decay from nanotubes of the same ͑n , m͒ type follows a single exponential decay function, however, with lifetimes varying between about 1 and 40 ps from nanotube to nanotube. A correlation between broad photoluminescence spectra and short lifetimes was found and explained by defects promoting both nonradiative decay and vibronic dephasing. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2913009͔Based on their exceptional optical properties, singlewalled carbon nanotubes ͑SWNT͒ will eventually play an important role as nanometer-scale building blocks for optoelectronics, nanoelectronics, and biosensing. 1-3 Experimental and theoretical studies confirmed the identification of the photoluminescent state as being excitonic in nature with extremely large exciton binding energies. 4,5 The excited state energies and dynamics of SWNT attracted particular scientific interest motivated by their unique one-dimensional structure combining intriguing optical and transport properties. To date, a large number of ensemble studies using pump-probe and time-resolved photoluminescence ͑PL͒ spectroscopy exist, reporting on mono-or multiexponential relaxation dynamics with decay times ranging from few to several tens of picoseconds for different sample materials. 4,6,7 Temperature dependent PL measurements suggest that the excited state relaxation reflects a complex interplay between excitonic states of different parity that are optically bright or dark depending on their accessibility from the ground state. 8,9 At present, excited state lifetimes are thought to be limited by fast transitions to these dark states but also by quenching related to defect related trap states. Transitions between excitonic states of different parity are expected to require symmetry breaking defects or environmental perturbations. 10 Defects and environmental coupling are spatially localized by nature and a unique property of a given nanotube. As a result, ensemble measurements will always represent an averaging. Previous single nanotube PL measurements revealed a distribution of lifetimes for a single nanotube chirality ͑6,4͒ ranging from sub 20 to 180 ps with an average value of 57 ps at 87 K. 11 These studies were limited to low temperatures because of the time resolution of the utilized system. In this paper, we report on the first time-resolved PL measurements of individual ͑6,4͒ and ͑6,5͒ SWNT at room temperature. PL transients extending over more than four orders of magnitude were found to be monoexponential with lifetimes ranging from about 1 to 40 ps.Single nanotube measurements were performed using an inverted confocal microscope in combination with electronics for time-correlated single-photon counting. Laser excitation is provided by a femtosecond Ti:sapphire laser operating at 760 nm and a repetition rate of 76 MHz. A high numerical aperture obje...

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“…At very high excitation intensity, when the number of excitons per SWNT is larger (much larger) than one, the exciton-exciton (Auger recombination) decay mechanism [81] is important. A similar exciton-electron Auger recombination was shown to be less efficient [82,83] than the multi-exciton channel due to strong restrictions imposed on the symmetry of electronic states participating in such a transition. These symmetry conditions are difficult to satisfy in a two-particle process, unless there are bound electrons in deep (mid-band-gap), strongly localized states or numerous free charge carriers in conduction or valence bands.…”

Section: Si: Discussion Of Alternative Recombination Mechanismsmentioning

confidence: 99%

Two-color spectroscopy of UV excited ssDNA complex with a single-wall nanotube photoluminescence probe: Fast relaxation by nucleobase autoionization mechanism

et al. 2016

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SWNT ssDNADNA is capable to recover after absorbing ultraviolet (UV) radiation, for example, by autoionization (AI). Singlewall carbon nanotube (SWNT) two-color photoluminescence spectroscopy was combined with quantum mechanical calculations to explain the AI in self-assembled complexes of DNA wrapped around SWNT. DNA autoionization is a fundamental process wherein UV-photoexcited nucleobases dissipate energy by charge transfer to the environment without undergoing chemical damage. Here, single-wall carbon nanotubes (SWNT) are explored as a photoluminescent reporter for studying the mechanism and rates of DNA autoionization. Two-color photoluminescence spectroscopy allows separate photoexcitation of the DNA and the SWNTs in the UV and visible range, respectively. A strong SWNT photoluminescence quenching is observed when the UV pump is resonant with the DNA absorption, consistent with charge transfer from the excited states of the DNA to the SWNT. Semiempirical calculations of the DNA-SWNT electronic structure, combined with a Green's function theory for charge transfer, show a 20 fs autoionization rate, dominated by the hole transfer. Rate-equation analysis of the spectroscopy data confirms that the quenching rate is limited by the thermalization of the free charge carriers transferred to the nanotube reservoir. The developed approach has a great potential for monitoring DNA excitation, autoionization, and chemical damage both in vivo and in vitro arXiv:1512.00710v1 [cond-mat.mes-hall] 2 Dec 2015 2

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Pump-Probe Spectroscopy of Exciton Dynamics in (6,5) Carbon Nanotubes

Cited by 115 publications

References 32 publications

Energy transfer pathways in semiconducting carbon nanotubes revealed using two-dimensional white-light spectroscopy

Energy transfer pathways in semiconducting carbon nanotubes revealed using two-dimensional white-light spectroscopy

Exciton decay dynamics in individual carbon nanotubes at room temperature

Two-color spectroscopy of UV excited ssDNA complex with a single-wall nanotube photoluminescence probe: Fast relaxation by nucleobase autoionization mechanism

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