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Surface Plasmon Resonance Evaluation of Colloidal Metal Aerogel FiltersSurface plasmon resonance imaging has in the past been applied to the characterization of thin films. In this study we apply the surface plasmon technique not to determine macroscopic spatial variations but rather to determine average microscopic information. Specifically, we deduce the dielectric properties of the surrounding gel matrix and information concerning the dynamics of the gelation process from the visible absorption characteristics of colloidal metal nanoparticles contained in aerogel pores. We have fabricated aerogels containing gold and silver nanoparticles. Because the dielectric constant of the metal particles is linked to that of the host matrix at the surface plasmon resonance, any change 'in the dielectric constant of the material surrounding the metal nanoparticles results in a shift in the surface plasmon wavelength. During gelation the surface plasmon resonance shifts to the red as the average or effective dielectric constant of the matrix increases. Conversely, formation of an aerogel or xerogel through supercritical extraction or evaporation of the solvent produces a blue shift in the resonance indicating a decrease in the dielectric constant of the matrix. From the magnitude of this shift we deduce the average fraction of air and of silica in contact with the metal particles. The surface area of metal available for catalytic gas reaction may thus be determined.
Document ID
19990097527
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Smith, David D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Sibille, Laurent
(Universities Space Research Association Huntsville, AL United States)
Cronise, Raymond J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Noever, David A.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1997
Subject Category
Nonmetallic Materials
Meeting Information
Meeting: Aerogels
Location: Montpellier
Country: France
Start Date: September 8, 1997
End Date: September 10, 1997
Distribution Limits
Public
Copyright
Other

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