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Proceedings Paper

Light-scattering spectra of colloidal gold aggregates: experimental measurements and theoretical simulations
Author(s): Vladimir A. Bogatyrev; Boris A. Medvedev; Lev A. Dykman; Nikolai G. Khlebtsov
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Paper Abstract

We report on the experimental spectra of light scattered at 90 degrees by colloidal gold particles (diameter 30 nm) and aggregates built from these particles during the salt aggregation process. The time dependence of spectra in the range 350-850 nm was measured by using a luminescence attachment to Specord M-40 spectrophotometer. The aggregation of sol was accompanied by essential increasing the single particle spectrum maximum (near 580 nm), its displacement to the red part in the spectrum, and by a broadening of the long wavelength wing of extinction. To explain these findings, we used a computer diffusion-limited cluster-cluster aggregation model. The optical properties of aggregates including light scattering spectra were computed by the coupled dipole method (CDM or DDA). The bulk optical constants of metals were modified by the size-limiting effect of nanoparticles. Our calculations showed a direct correlation between cluster particle number (Nequals10-50) and intensity of scattered light. However, this correlation failed for 100-particle clusters. It can be supposed that DDA model is not adequate for accurate prediction of light scattering properties of large aggregates.

Paper Details

Date Published: 4 May 2001
PDF: 7 pages
Proc. SPIE 4241, Saratov Fall Meeting 2000: Optical Technologies in Biophysics and Medicine II, (4 May 2001); doi: 10.1117/12.431503
Show Author Affiliations
Vladimir A. Bogatyrev, Institute of Biochemistry and Physiology of Plants and Microorganisms and Saratov State Un (Russia)
Boris A. Medvedev, Institute of Biochemistry and Physiology of Plants and Microorganisms (Russia)
Lev A. Dykman, Institute of Biochemistry and Physiology of Plants and Microorganisms (Russia)
Nikolai G. Khlebtsov, Institute of Biochemistry and Physiology of Plants and Microorganisms and Saratov State Un (Russia)


Published in SPIE Proceedings Vol. 4241:
Saratov Fall Meeting 2000: Optical Technologies in Biophysics and Medicine II
Valery V. Tuchin, Editor(s)

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