Excitation Isotropy of Single CdSe/ZnS Nanocrystals

Chizhik, Alexey I.; Chizhik, Anna M.; Khoptyar, Dmitry; Bär, Sebastian; Meixner, Alfred J.

doi:10.1021/nl1040385

Cited by 49 publications

(56 citation statements)

References 39 publications

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“…The particles were excited with an azimuthally polarized laser beam of 485 nm wavelength, focused into a diffraction-limited spot using a 1.49 numerical aperture objective lens. The azimuthal polarization of the excitation light allowed us to verify that every measured SiO 2 NP behaves indeed as a single dipole emitter (figure 1(c)) 26 . Further details of the SiO 2 NPs synthesis and PL measurements can be found in the Supplementary Information.…”

Section: Resultsmentioning

confidence: 90%

Photoluminescence of a single quantum emitter in a strongly inhomogeneous chemical environment

Chizhik

Tarpani

Latterini

et al. 2015

Phys. Chem. Chem. Phys.

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We present the results of a comprehensive photoluminescence study of defect centres in single SiO2 nanoparticles. We show that the photo-physical properties of the luminescent centres strongly resemble those of single dye molecules. However, these properties exhibit a large variability from particle to particle due to the different local chemical environment around each centre of each particle. This variability provides new insight into the complex photo-physics of single quantum emitters embedded into a random chemical environment. Moreover, a better understanding of the fundamental mechanism of the photoluminescence of defect centres in SiO2 structure is paramount for their application as white-light sources, non-toxic labels for bio-imaging, or for combining them with metallic and semiconductor nanostructures.

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Section: Resultsmentioning

confidence: 90%

Photoluminescence of a single quantum emitter in a strongly inhomogeneous chemical environment

Chizhik

Tarpani

Latterini

et al. 2015

Phys. Chem. Chem. Phys.

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“…For this reason, for a 1D dipole, one can write Iðα exc Þ ∝ jd:Ẽ exc j 2 ∝ I 0 jũ d :ũ α j 2 ¼ I 0 cos 2 ðΦ − α exc Þsin 2 Θ: (37) In this case, as pointed out in earlier work on singlemolecule orientation [1,10], the in-plane angle Φ can be obtained as the angle α exc that maximizes Iðα exc Þ, but the out-of-plane angle Θ cannot be obtained because the value I 0 is not known. It is clear, by comparison of expressions (25) and (37), that the polarization analyses in excitation and emission are two very different situations.…”

Section: Theoretical Resultsmentioning

confidence: 99%

Measurement of Three-Dimensional Dipole Orientation of a Single Fluorescent Nanoemitter by Emission Polarization Analysis

et al. 2014

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International audienceWe demonstrate theoretically and experimentally that the three-dimensional orientation of a single fluorescent nanoemitter can be determined by polarization analysis of the emitted light (while excitation polarization analysis provides only the in-plane orientation). The determination of the emitter orientation by polarimetry requires a theoretical description, including the objective numerical aperture, the 1D or 2D nature of the emitting dipole, and the environment close to the dipole. We develop a model covering most experimentally relevant microscopy configurations and provide analytical relations that are useful for orientation measurements. We perform polarimetric measurements on high-quality core-shell CdSe/CdS nanocrystals and demonstrate that they can be approximated by two orthogonal degenerated dipoles. Finally, we show that the orientation of a dipole can be inferred by polarimetric measurement, even for a dipole in the vicinity of a gold film, while in this case, the well-established defocused microscopy is not appropriate

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“…It is not clear if this effect may operate in three-dimensional carbon nanostructures. Also, the nanoscale systems with loosely bound excitons confined in all three directions display optically isotropic fluorescence response [212] and because of such isotropic three-dimensional behavior, the QDs are considered as "dots". However, in some rare cases the excitation transition dipole moment was observed (e.g., in single silicon nanocrystals) and it is attributed to local defect centers [212].…”

Section: On the Involvement Of Wannier-mott Loosely Bound Excitonsmentioning

confidence: 99%

“…Also, the nanoscale systems with loosely bound excitons confined in all three directions display optically isotropic fluorescence response [212] and because of such isotropic three-dimensional behavior, the QDs are considered as "dots". However, in some rare cases the excitation transition dipole moment was observed (e.g., in single silicon nanocrystals) and it is attributed to local defect centers [212]. Still, the analogy of carbon nanostructures with such systems is unclear and the numerous experimental data on C-dots show high level of their optical anisotropy on excitation by polarized light (see Section 5.2).…”

Section: On the Involvement Of Wannier-mott Loosely Bound Excitonsmentioning

confidence: 99%

Excitons in Carbonic Nanostructures

Demchenko

2019

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Unexpectedly bright photoluminescence emission can be observed in materials incorporating inorganic carbon when their size is reduced from macro–micro to nano. At present, there is no consensus in its understanding, and many suggested explanations are not consistent with the broad range of experimental data. In this Review, I discuss the possible role of collective excitations (excitons) generated by resonance electronic interactions among the chromophore elements within these nanoparticles. The Förster-type resonance energy transfer (FRET) mechanism of energy migration within nanoparticles operates when the composing fluorophores are the localized electronic systems interacting at a distance. Meanwhile, the resonance interactions among closely located fluorophores may lead to delocalization of the excited states over many molecules resulting in Frenkel excitons. The H-aggregate-type quantum coherence originating from strong coupling among the transition dipoles of adjacent chromophores in a co-facial stacking arrangement and exciton transport to emissive traps are the basis of the presented model. It can explain most of the hitherto known experimental observations and must stimulate the progress towards their versatile applications.

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Excitation Isotropy of Single CdSe/ZnS Nanocrystals

Cited by 49 publications

References 39 publications

Photoluminescence of a single quantum emitter in a strongly inhomogeneous chemical environment

Photoluminescence of a single quantum emitter in a strongly inhomogeneous chemical environment

Measurement of Three-Dimensional Dipole Orientation of a Single Fluorescent Nanoemitter by Emission Polarization Analysis

Excitons in Carbonic Nanostructures

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