Measurements for molar extinction coefficients of aqueous quantum dots

The focus on heavy metal-free visible emitters in optoelectronic devices has increased interest in ZnSe semiconductor quantum dots (QDs) over the past decade. Empirical fit equations correlating the lowest energy electron transition to their size and molar extinction coefficients (ε) are often used to determine the concentration of suspensions containing QDs. This is essential to the design and successful synthesis of complex semiconductor nanoparticles including core/shell and dot-in-rod heterostructures as well as consistent device fabrication. While these equations are known and heavily used for CdSe, CdTe, CdS, PbS, etc., they are not well established for ZnSe nanocrystals; the only two reports of ε in the literature differ by over an order of magnitude. In this study, a series of ZnSe QDs with diameters ranging from 2 to 6 nm were characterized with small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and UV-Vis spectroscopy. SAXS-based size analysis enabled practical inclusion of small particles in the evaluation. Elemental analysis with microwave plasma atomic emission spectroscopy (MP-AES) yields a non-stoichiometric Zn:Se ratio consistent with zinc-terminated spherical ZnSe QDs. Using these combined results, molar extinction coefficients for each QD sample were calculated. Empirical fit equations correlating QD size with its lowest energy electron transition (i.e., 1S peak position) and molar extinction coefficients for both 1S peak and high energy wavelengths are reported. These results will enable the consistent and reliable use of ZnSe core particles in complex heterostructures and devices.

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Near-infrared Ag2Se quantum dots with distinct absorption features and high fluorescence quantum yields

RSC Advances ◽

10.1039/c6ra04987g ◽

2016 ◽

Vol 6 (44) ◽

pp. 38183-38186 ◽

Cited By ~ 18

Author(s):

Li-Juan Shi ◽

Chun-Nan Zhu ◽

He He ◽

Dong-Liang Zhu ◽

Zhi-Ling Zhang ◽

...

Keyword(s):

Quantum Dots ◽

Near Infrared ◽

Quantum Yields ◽

Extinction Coefficients ◽

Fluorescence Quantum Yields ◽

High Fluorescence ◽

Absorption Features ◽

Molar Extinction Coefficients

Near-infrared Ag2Se QDs with distinct absorption features ranging between 830–954 nm and fluorescence quantum yields up to 23.4% were controllably synthesized, and the molar extinction coefficients of the Ag2Se QDs were determined.

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ZnSe Quantum Dots: Determination of Molar Extinction Coefficients for UV to Blue Emitters

10.26434/chemrxiv.13363706.v1 ◽

2020 ◽

Author(s):

Reyhaneh Toufanian ◽

Xingjian Zhong ◽

Joshua Kays ◽

Alexander Saeboe ◽

Allison Dennis

Keyword(s):

Quantum Dots ◽

Microwave Plasma ◽

Electron Transition ◽

High Energy ◽

Device Fabrication ◽

Energy Electron ◽

Size Analysis ◽

Extinction Coefficients ◽

Vis Spectroscopy ◽

Molar Extinction Coefficients

The focus on heavy metal-free visible emitters in optoelectronic devices has increased interest in ZnSe semiconductor quantum dots (QDs) over the past decade. Empirical fit equations correlating the lowest energy electron transition to their size and molar extinction coefficients (ε) are often used to determine the concentration of suspensions containing QDs. This is essential to the design and successful synthesis of complex semiconductor nanoparticles including core/shell and dot-in-rod heterostructures as well as consistent device fabrication. While these equations are known and heavily used for CdSe, CdTe, CdS, PbS, etc., they are not well established for ZnSe nanocrystals; the only two reports of ε in the literature differ by over an order of magnitude. In this study, a series of ZnSe QDs with diameters ranging from 2 to 6 nm were characterized with small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and UV-Vis spectroscopy. SAXS-based size analysis enabled practical inclusion of small particles in the evaluation. Elemental analysis with microwave plasma atomic emission spectroscopy (MP-AES) yields a non-stoichiometric Zn:Se ratio consistent with zinc-terminated spherical ZnSe QDs. Using these combined results, molar extinction coefficients for each QD sample were calculated. Empirical fit equations correlating QD size with its lowest energy electron transition (i.e., 1S peak position) and molar extinction coefficients for both 1S peak and high energy wavelengths are reported. These results will enable the consistent and reliable use of ZnSe core particles in complex heterostructures and devices.

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ZnSe Quantum Dots: Determination of Molar Extinction Coefficient for UV to Blue Emitters

10.26434/chemrxiv.13363706.v2 ◽

2020 ◽

Author(s):

Reyhaneh Toufanian ◽

Xingjian Zhong ◽

Joshua Kays ◽

Alexander Saeboe ◽

Allison Dennis

Keyword(s):

Quantum Dots ◽

Microwave Plasma ◽

Electron Transition ◽

High Energy ◽

Device Fabrication ◽

Energy Electron ◽

Size Analysis ◽

Extinction Coefficients ◽

Vis Spectroscopy ◽

Molar Extinction Coefficients

The focus on heavy metal-free visible emitters in optoelectronic devices has increased interest in ZnSe semiconductor quantum dots (QDs) over the past decade. Empirical fit equations correlating the lowest energy electron transition to their size and molar extinction coefficients (ε) are often used to determine the concentration of suspensions containing QDs. This is essential to the design and successful synthesis of complex semiconductor nanoparticles including core/shell and dot-in-rod heterostructures as well as consistent device fabrication. While these equations are known and heavily used for CdSe, CdTe, CdS, PbS, etc., they are not well established for ZnSe nanocrystals; the only two reports of ε in the literature differ by over an order of magnitude. In this study, a series of ZnSe QDs with diameters ranging from 2 to 6 nm were characterized with small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and UV-Vis spectroscopy. SAXS-based size analysis enabled practical inclusion of small particles in the evaluation. Elemental analysis with microwave plasma atomic emission spectroscopy (MP-AES) yields a non-stoichiometric Zn:Se ratio consistent with zinc-terminated spherical ZnSe QDs. Using these combined results, molar extinction coefficients for each QD sample were calculated. Empirical fit equations correlating QD size with its lowest energy electron transition (i.e., 1S peak position) and molar extinction coefficients for both 1S peak and high energy wavelengths are reported. These results will enable the consistent and reliable use of ZnSe core particles in complex heterostructures and devices.

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ASSOCIATION OF CERIC IONS WITH SULPHATE (A SPECTRAL STUDY)

Canadian Journal of Chemistry ◽

10.1139/v51-095 ◽

1951 ◽

Vol 29 (10) ◽

pp. 828-837 ◽

Cited By ~ 123

Author(s):

T. J. Hardwick ◽

E. Robertson

Keyword(s):

Spectral Study ◽

Association Constants ◽

Extinction Coefficients ◽

Ceric Ion ◽

Molar Extinction Coefficients

Ceric ion has been shown to associate with sulphate ion to form successively Ce(SO4++, Ce(SO4)2, and Ce(SO4)3−. The association constants relating these species have been determined at 25 °C. The molar extinction coefficients of each associated complex have been found between 395 and 430 mμ. Migration experiments bear out the results qualitatively.

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Synthesis and characterization of meso-to-meso directly linked porphyrin-diazaporphyrin triads

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424618500633 ◽

2018 ◽

Vol 22 (09n10) ◽

pp. 814-820

Author(s):

Yingying Jia ◽

Ling Xu ◽

Bangshao Yin ◽

Mingbo Zhou ◽

Jianxin Song

Keyword(s):

Nickel Complex ◽

High Resolution Mass Spectrometry ◽

Dihedral Angles ◽

X Ray Diffraction ◽

Extinction Coefficients ◽

X Ray ◽

H Nmr ◽

First Time ◽

Molar Extinction Coefficients

Beginning with 5,10,15-triarylporphyrin-nickel complex, five meso-to-meso directly linked porphyrin-diazaporphyrin triads were successfully prepared for the first time through a series of reactions including formylation via Vilsmeier–Haack reaction, condensation with pyrrole, bromination with [Formula: see text]-Bromosuccinimide (NBS), oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), metal-templated cyclization of dibromodipyrrin-metal complexes with NaN[Formula: see text] and demetalization. All these triads were comprehensively characterized by [Formula: see text]H NMR, high-resolution mass spectrometry and UV-vis absorption. In addition, the structure of compound 6Ni was unambiguously determined by X-ray diffraction analysis, which showed that the two dihedral angles are both 86.65 (4)[Formula: see text] between each mean plane of porphyrin and that of central diazaporphyrin The UV-vis absorption spectra disclosed that the longest wavelengths of Soret bands and Q bands for these triads were observed at 429 and 642 nm, respectively. In contrast to diazaporphyrin-porphyrin dyads, diazaporphyrin dimers and diazaporphyrin monomers reported previously the molar extinction coefficients, particularly for triad 8Ni are much higher.

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