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Porous Sol–Gel Silicates Containing Gold Particles as Matrices for Surface‐EnhancedRaman Spectroscopy
Author(s) -
Akbarian Fatemeh,
Dunn Bruce S.,
Zink Jeffrey I.
Publication year - 1996
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199610)27:10<775::aid-jrs28>3.0.co;2-8
Subject(s) - raman spectroscopy , materials science , chemical engineering , colloidal gold , particle size , particle (ecology) , silicate , porous glass , absorption spectroscopy , matrix (chemical analysis) , porosity , nanoparticle , nanotechnology , composite material , optics , oceanography , physics , engineering , geology
Silicate glass made by the sol–gel technique containing physically encapsulated gold particles is a unique matrix for surface‐enhanced Raman spectroscopy (SERS). The matrix is optically transparent and contains pores that are large enough to allow small molecules such as pyridine and pyrazine in solution to diffuse through the solid glass to the gold particles (diameters of the order of 100 Å). Two methods of preparing the glass are discussed. A photochemical method uses organometallic gold precursor compounds that are dissolved in the sol and encapsulated in the growing silicate network. UV irradiation of the doped monoliths causes the photodeposition of gold particles within the silica gel or xerogel. The particle size is controlled by the irradiation time and by the form of the matrix at the time of deposition. Second, colloidal gold in aqueous solution is mixed with the sol and the inorganic glass forms around the particles. The particles are characterized by their electronic absorption spectra, x‐ray diffraction and transmission electron microscopy. The transparent, porous monoliths are excellent substrates for SERS. The sol–gel matrix stabilizes the gold particles (in comparison with colloids in liquid media) and SERS can be used to detect molecules that penetrate the matrix. The SERS effect is verified by the enhancement of the Raman bands and by the changes in their polarization ratio.