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Photochemical incorporation of silver quantum dots in monodisperse silica colloids for photonic crystal applications

Wang, W and Asher, SA (2001) Photochemical incorporation of silver quantum dots in monodisperse silica colloids for photonic crystal applications. Journal of the American Chemical Society, 123 (50). 12528 - 12535. ISSN 0002-7863

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Abstract

We developed a novel method to fabricate nanocomposite monodisperse SiO 2 spheres (∼ 100 nm) containing homogeneously dispersed Ag quantum dots (2∼5 nm). The inclusion morphology is controlled through the timing of the photochemical reduction of silver ions during hydrolysis of tetraethoxysilane in a microemulsion. Depending on the timing, Ag quantum dots can be directed to different annuli within the SiO 2 spheres, as well as onto the SiO 2 sphere surfaces. The embedded Ag quantum dots show a plasmon resonance absorption band at 438 nm. These Ag@SiO 2 particles have significant surface charge and readily self-assemble into crystalline colloidal array (CCA) photonic crystals which Bragg-diffract light in the visible region. The magnitude of the plasmon resonance absorption depends on the CCA Bragg diffraction condition. The negative dielectric constant of the silver nanoparticles may be decreasing the silica-silver nanodot composite refractive index below that of the water medium. We may be observing an analogue of the Borrmann effect previously observed in X-ray scattering, where the incident and diffracted electric field standing wave becomes localized in regions of small CCA crystal absorption.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Wang, W
Asher, SAasher@pitt.eduASHER
Date: 19 December 2001
Date Type: Publication
Journal or Publication Title: Journal of the American Chemical Society
Volume: 123
Number: 50
Page Range: 12528 - 12535
DOI or Unique Handle: 10.1021/ja011262j
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 0002-7863
PubMed ID: 11741416
Date Deposited: 20 Mar 2013 16:44
Last Modified: 12 Oct 2017 08:56
URI: http://d-scholarship.pitt.edu/id/eprint/17788

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