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Size selection of colloidal gold aggregates by filtration: effect on surface‐enhanced Raman scattering intensities
Author(s) -
Freeman R. Griffith,
Bright Robin M.,
Hommer Michael B.,
Natan Michael J.
Publication year - 1999
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(199908)30:8<733::aid-jrs433>3.0.co;2-e
Subject(s) - colloid , chemistry , particle size , raman scattering , filtration (mathematics) , particle (ecology) , raman spectroscopy , analytical chemistry (journal) , aggregate (composite) , membrane , chemical physics , nanotechnology , chemical engineering , materials science , chromatography , optics , physics , statistics , mathematics , engineering , biochemistry , oceanography , geology
The effect of colloidal Au particle aggregation on surface‐enhanced Raman scattering (SERS) spectra was probed by SERS filtration experiments. In this approach, SERS and optical spectra were recorded for trans ‐1,2‐bis(4‐pyridyl)ethylene (BPE)‐aggregated solutions of colloidal Au filtered through straight‐channel membranes with successively smaller diameters. This allowed the overall SERS intensity to be factored into aggregate size‐dependent contributions. Experiments were carried out as a function of adsorbate concentration (0.5–2.5 µ M BPE) and initial particle size (12–50 nm diameter colloidal Au). The key findings are as follows: (i) under conditions of minimal aggregation, appreciable SERS intensity derives from aggregates with effective diameters less than 200 nm; (ii) the amount of aggregant clearly controls the average aggregate size; and (iii) similarly aggregated solutions based on different diameter colloidal Au particles give different distributions of aggregates. These studies provide an insight into the dynamics of colloidal Au aggregation, suggest a procedure for signal optimization in colloid SERS experiments, and set the stage for controlled surface confinement of SERS‐active particle clusters. Copyright © 1999 John Wiley & Sons, Ltd.