Using two-dimensional photon echo spectroscopy to probe the fine structure of the ground state biexciton of CdSe nanocrystals

Wong, C.; Scholes, Gregory D.

doi:10.1016/j.jlumin.2010.09.015

Cited by 31 publications

(55 citation statements)

References 44 publications

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“…This electronic structure results in positive (stimulated emission/ground state bleach) and negative (excited state absorption) signatures, which can be probed to follow the electronic dynamics and the binding energy of biexcitons [73–77]. Previous 2D spectroscopy on QDs primarily focused on the band-edge exciton or the first two excitons, which are primarily associated with the lowest lying excited electronic state [16,78,79]. Recent work, however, has shown that the nonlinear response varies depending on which state is initially excited, with the largest difference occurring upon initial excitation into the 1P(e) higher lying electron manifold [61,80].…”

Section: Discussionmentioning

confidence: 99%

Dispersion-free continuum two-dimensional electronic spectrometer

et al. 2014

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Electronic dynamics span broad energy scales with ultrafast time constants in the condensed phase. Two-dimensional (2D) electronic spectroscopy permits the study of these dynamics with simultaneous resolution in both frequency and time. In practice, this technique is sensitive to changes in nonlinear dispersion in the laser pulses as time delays are varied during the experiment. We have developed a 2D spectrometer that uses broadband continuum generated in argon as the light source. Using this visible light in phase-sensitive optical experiments presents new challenges in implementation. We demonstrate all-reflective interferometric delays using angled stages. Upon selecting an ~180 nm window of the available bandwidth at ~10 fs compression, we probe the nonlinear response of broadly absorbing CdSe quantum dots and electronic transitions of Chlorophyll a.

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Section: Discussionmentioning

confidence: 99%

Dispersion-free continuum two-dimensional electronic spectrometer

et al. 2014

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“…Several groups have begun to implement the 2DES technique to study the electronic structure and dynamics of colloidal semiconductor nanocrystals. [65][66][67][68][69][70][71][72][73] An alternative 2D technique consisting of detecting an incoherent signal after the interaction of a fourth pulse was recently applied to the study of PbS quantum dots. [ 74 ] The last pulse in these experiments converts the fi nal optical coherence once again to a population state that is directly measured by detecting the resulting (incoherent) fl uorescence or photocurrent signal.…”

Section: Coherent Multidimensional Spectroscopiesmentioning

confidence: 99%

Two‐Dimensional Visible Spectroscopy For Studying Colloidal Semiconductor Nanocrystals

Cassette

Dean

Scholes

2016

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Possibilities offered by 2D visible spectroscopy for the investigation of the properties of excitons in colloidal semiconductor nanocrystals are overviewed, with a particular focus on their ultrafast dynamics. The technique of 2D electronic spectroscopy is illustrated with several examples showing its advantages compared to 1D ultrafast spectroscopic techniques (transient absorption and time-resolved photoluminescence).

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“…57,58 Furthermore, various mixed-biexcitonic states are possible, especially at early times prior to charge carrier relaxation to the band-edge. 33,40…”

Section: B Femtosecond Nonlinear Spectroscopy Of Quantum Dotsmentioning

confidence: 99%

“…37,38 These techniques illuminate relaxation dynamics with great accuracy, but can convolve contributions from many sources of disorder in nanocrystals, precluding a detailed understanding of the distinct roles of static disorder, such as size polydispersity, and dynamic disorder, such as coupling to the environment. Other methods successfully probe fluctuations and inhomogeneity including photon echo peak shift experiments, [39][40][41] hole-burning, 22,42 and 2DES 40,[43][44][45][46] but have been focused on the band edge or two lowest-lying excitonic states, for which the dynamics correspond mainly to hole relaxation. Recent 2DES work with broadband pulses on smaller dots by Turner et al 44 demonstrate electronic coherence between the two lowest lying excited states.…”

Section: Introductionmentioning

confidence: 99%

Exploring size and state dynamics in CdSe quantum dots using two-dimensional electronic spectroscopy

Caram

Zheng

Dahlberg

et al. 2014

The Journal of Chemical Physics

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Development of optoelectronic technologies based on quantum dots depends on measuring, optimizing, and ultimately predicting charge carrier dynamics in the nanocrystal. In such systems, size inhomogeneity and the photoexcited population distribution among various excitonic states have distinct effects on electron and hole relaxation, which are difficult to distinguish spectroscopically. Two-dimensional electronic spectroscopy can help to untangle these effects by resolving excitation energy and subsequent nonlinear response in a single experiment. Using a filament-generated continuum as a pump and probe source, we collect two-dimensional spectra with sufficient spectral bandwidth to follow dynamics upon excitation of the lowest three optical transitions in a polydisperse ensemble of colloidal CdSe quantum dots. We first compare to prior transient absorption studies to confirm excitation-state-dependent dynamics such as increased surface-trapping upon excitation of hot electrons. Second, we demonstrate fast band-edge electron-hole pair solvation by ligand and phonon modes, as the ensemble relaxes to the photoluminescent state on a sub-picosecond time-scale. Third, we find that static disorder due to size polydispersity dominates the nonlinear response upon excitation into the hot electron manifold; this broadening mechanism stands in contrast to that of the band-edge exciton. Finally, we demonstrate excitation-energy dependent hot-carrier relaxation rates, and we describe how two-dimensional electronic spectroscopy can complement other transient nonlinear techniques.

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Using two-dimensional photon echo spectroscopy to probe the fine structure of the ground state biexciton of CdSe nanocrystals

Cited by 31 publications

References 44 publications

Dispersion-free continuum two-dimensional electronic spectrometer

Dispersion-free continuum two-dimensional electronic spectrometer

Two‐Dimensional Visible Spectroscopy For Studying Colloidal Semiconductor Nanocrystals

Exploring size and state dynamics in CdSe quantum dots using two-dimensional electronic spectroscopy

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