Threshold for quasicontinuum absorption and reduced luminescence efficiency in CdSe nanocrystals

Hoheisel, W.; Colvin, Vicki L.; Johnson, Christopher; Alivisatos, A. Paul

doi:10.1063/1.468107

Cited by 155 publications

(157 citation statements)

References 18 publications

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“…We observed an anomalous dependence of quantum yields on the excitation wavelengths especially at wavelengths shorter than 420nm. This behavior is consistent with published literature on dots (16,17). Photo excitation of QD585 in the wavelength window between 420 and 500 nm yielded, on average, a uniform quantum efficiency of ≈ 0.20.…”

Section: Introductionsupporting

confidence: 91%

The development of quantum dot calibration beads and quantitative multicolor bioassays in flow cytometry and microscopy

Campos

López

et al. 2007

Analytical Biochemistry

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The use of fluorescence calibration beads has been the hallmark of quantitative flow cytometry. It has enabled the direct comparison of inter-laboratory data as well as quality control in clinical flow cytometry. In this paper we have described a simple method for producing color-generalizable calibration beads based on streptavidin functionalized quantum dots. Based on their broad absorption spectra and relatively narrow emission, that is tunable on the basis of dot-size, quantum dot calibration beads can be made for any fluorophore that matches their emission color. In an earlier publication (1) we characterized the spectroscopic properties of commercial streptavidin functionalized dots (Invitrogen). Here we describe the molecular assembly of these dots on biotinylated beads. The law of mass action is used to readily define the site densities of the dots on the beads. The applicability of these beads is tested against the industry standard, commercial fluorescein calibration beads. The utility of the calibration beads are also herein extended to the characterization surface densities of dot-labeled epidermal growth factor ligands as well as quantitative indicators of the binding of dotlabeled virus particles to cells.

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Section: Introductionsupporting

confidence: 91%

The development of quantum dot calibration beads and quantitative multicolor bioassays in flow cytometry and microscopy

Campos

López

et al. 2007

Analytical Biochemistry

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“…The emission yield of the QD525 dots also significantly drops to 15% at 350 nm from a high of 40% at 450 nm. The level of drop (≤50%) in quantum yield at the high-energy end for both samples is consistent with literature reports (16,52). The difference in behavior between the QD525 and QD585 dots appears to originate more from differences in size distribution rather than intrinsic properties where the smaller QD525 dots appear to be more heterogeneous (c.f.…”

Section: On the Correspondence Of Absorption And Photoexcitation Specsupporting

confidence: 79%

“…Experimental data have shown a strong correlation between the method of dot preparation and excited state behavior (23). Several authors reported a decrease of emission yield with decreasing wavelength, suggesting an anomalous dependence of excitation on wavelength (24,25,37,38,52). Potential mechanisms for this process have been postulated, including the hypothesized existence of electronic relaxation channels of "hot" electrons, which bypass the lowest excited state (37,38).…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic characterization of streptavidin functionalized quantum dots

López

Sklar

et al. 2007

Analytical Biochemistry

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The spectroscopic properties of quantum dots can be strongly influenced by the conditions of their synthesis. In this work we have characterized several spectroscopic properties of commercial, streptavidin functionalized quantum dots (QD525, lot#1005-0045 and QD585, Lot#0905-0031 from Invitrogen). This is the first step in the development of calibration beads, to be used in a generalizable quantification scheme of multiple fluorescent tags in flow cytometry or microscopy applications. We used light absorption, photoexcitation, and emission spectra, together with excited-state lifetime measurements to characterize their spectroscopic behavior, concentrating on the 400-500nm wavelength ranges that are important in biological applications. Our data show an anomalous dependence of emission spectrum, lifetimes, and quantum yield (QY) on excitation wavelength that is particularly pronounced in the QD525. For QD525, QY values ranged from 0.2 at 480nm excitation up to 0.4 at 450nm and down again to 0.15 at 350nm. For QD585, QY values were constant at 0.2 between 500nm and 400nm, but dropped to 0.1 at 350nm. We attribute the wavelength dependences to heterogeneity in size and surface defects in the QD525, consistent with characteristics previously described in the chemistry literature. The results are discussed in the context of bridging the gap between what is currently known in the physical chemistry literature of quantum dots, and the quantitative needs of assay development in biological applications.

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“…Moreover, the range of size of QDs in that work was 2-8 nm. In that and other works [3][4][5][6], authors assure that except excitonic peaks there is a wide luminescence band which is caused by the impurity and surface states.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the effect of polarization traps and shallow impurities on the interlevel light absorption of quantum dots

Boichuk¹,

Leshko²,

Karpyn³

2017

Condens. Matter Phys.

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A spherical quantum dot (QD) heterosystem CdS/SiO 2 has been studied. Each QD has a hydrogen-like impurity in its center. Besides that, it has been accounted that a polarization trap for electron exists at the interfaces due to the difference between the QD and matrix dielectric permittivity. It has been defined that for small QD radii there are surface electron states. For different radii, partial contributions of the surface states into the electron energy caused by the electron-ion and electron-polarization charges interaction have been defined. The linear light absorption coefficient of noninteracting QDs has been calculated taking into account the QD dispersion by the size. It is shown that the surface states can be observed into different ranges of an electromagnetic spectrum.

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Threshold for quasicontinuum absorption and reduced luminescence efficiency in CdSe nanocrystals

Cited by 155 publications

References 18 publications

The development of quantum dot calibration beads and quantitative multicolor bioassays in flow cytometry and microscopy

The development of quantum dot calibration beads and quantitative multicolor bioassays in flow cytometry and microscopy

Spectroscopic characterization of streptavidin functionalized quantum dots

Analysis of the effect of polarization traps and shallow impurities on the interlevel light absorption of quantum dots

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