Topic
Stokes shift
About: Stokes shift is a research topic. Over the lifetime, 3665 publications have been published within this topic receiving 98596 citations. The topic is also known as: stokes.
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TL;DR: The observed shortening of the luminescence decay time in CdSe nanoncrystals in a magnetic field is in excellent agreement with the theory, giving further support to the validity of the model.
Abstract: We present a theoretical analysis of the band-edge exciton structure in nanometer-size crystallites of direct semiconductors with a cubic lattice structure or a hexagonal lattice structure which can be described within the framework of a quasicubic model. The lowest energy exciton, eightfold degenerate in spherically symmetric dots, is split into five levels by the crystal shape asymmetry, the intrinsic crystal field (in hexagonal lattice structures), and the electron-hole exchange interaction. Transition oscillator strengths and the size dependence of the splittings have been calculated. Two of the five states, including the ground state, are optically passive (dark excitons). The oscillator strengths of the other three levels (bright excitons) depend strongly on crystal size, shape, and energy band parameters. The relative ordering of the energy levels is also heavily influenced by these parameters. The distance between the first optically active state and the optically forbidden ground exciton state increases with decreasing size, leading to an increase of the Stokes shift in the luminescence. Our results are in good agreement with the size dependence of Stokes shifts obtained in fluorescence line narrowing and photoluminescence experiments in CdSe nanocrystals. Mixing of the dark and bright excitons in an external magnetic field allows the direct optical recombination of the dark exciton ground state. The observed shortening of the luminescence decay time in CdSe nanoncrystals in a magnetic field is also in excellent agreement with the theory, giving further support to the validity of our model. \textcopyright{} 1996 The American Physical Society.
1,180 citations
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TL;DR: In this paper, the authors present a re-analysis of the FD-excitation, absorption, reflection, and emission spectra of Eu2+ in inorganic compounds.
882 citations
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TL;DR: The literature on 4f n ↔4f n −1 5d transitions of the trivalent lanthanides in inorganic compounds has been collected as mentioned in this paper from critically analyzing fd-excitation, absorption, reflection and df-emission spectra, values for the spectroscopic red shift of 5d levels and the stokes shift were determined.
853 citations
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TL;DR: In this article, the authors demonstrate that shape control may be achieved in the shell of colloidally grown semiconductor nanocrystals (independent of the core), allowing the combination of a 0-D spherical CdSe core with a 1-D rodlike CdS shell.
Abstract: We demonstrate that efficient shape control may be achieved in the shell of colloidally grown semiconductor nanocrystals (independent of the core), allowing the combination of a 0-D spherical CdSe core with a 1-D rodlike CdS shell. Besides exhibiting linearly polarized emission with a room-temperature quantum efficiency above 70%, these mixed-dimensionality colloidal heterostructures display large, length-dependent Stokes shifts as well as giant extinction coefficients approaching 107cm-1 M-1.
618 citations
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TL;DR: Magic-sized cadmium selenide (CdSe) nanocrystals have been pyrolytically synthesized and exhibit broadband emission that covers most of the visible spectrum while not suffering from self absorption.
Abstract: Magic-sized cadmium selenide (CdSe) nanocrystals have been pyrolytically synthesized. These ultra-small nanocrystals exhibit broadband emission (420−710 nm) that covers most of the visible spectrum while not suffering from self absorption. This behavior is a direct result of the extremely narrow size distribution and unusually large Stokes shift (40−50 nm). The intrinsic properties of these ultra-small nanocrystals make them an ideal material for applications in solid state lighting and also the perfect platform to study the molecule-to-nanocrystal transition.
618 citations