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Does shining light on gold colloids influence aggregation?

Bhattacharya S, Narasimha S, Roy A, Banerjee S - Sci Rep (2014)

Bottom Line: In the literature, the electrostatic interactions, van der Waals interactions, and the change in free energy due to ligand-ligand or ligand-solvent interactions are mainly considered to be the dominating factors in determining the characteristics of the gold aggregates.However, our light scattering and imaging experiments clearly indicate a distinct effect of light in the growth structure of the gold colloidal particles.We attribute this to the effect of a non-uniform distribution of the electric field in aggregated gold colloids under the influence of light.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Technology Kharagpur, India.

ABSTRACT
In this article we revisit the much-studied behavior of self-assembled aggregates of gold colloidal particles. In the literature, the electrostatic interactions, van der Waals interactions, and the change in free energy due to ligand-ligand or ligand-solvent interactions are mainly considered to be the dominating factors in determining the characteristics of the gold aggregates. However, our light scattering and imaging experiments clearly indicate a distinct effect of light in the growth structure of the gold colloidal particles. We attribute this to the effect of a non-uniform distribution of the electric field in aggregated gold colloids under the influence of light.

No MeSH data available.


Surface plasmon resonance spectra of gold colloid of different concentrations.
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f1: Surface plasmon resonance spectra of gold colloid of different concentrations.

Mentions: Fig. 1 describes the surface plasmon resonance band of freshly prepared gold colloidal particles of various concentrations. All spectra exhibit the absorption peak at 525 nm. Neglecting the scattering of light by small particles and using Mie's solution to Maxwell's equations for dielectric spheres in a medium one can estimate the average size (diameter d) of the particles (monomers), using the observed resonance maxima2425. The average size of the particles in all concentration of the sol is estimated to be 22 nm. The resonance energy depends on various factors, e.g., average size of the particles in the sol, surface charge on the particles, dielectric constant of the medium, etc. We observe in Fig. 1 that none of the parameters of the spectral line profile, except the intensity of the resonance peak, change with dilution. Thus, it is reasonable to believe that the dilution decreases the volume fraction of the particles in the sol, but the characteristics of the colloidal system governing the interactions between the colloidal particles, the ligand, and the medium remain unchanged.


Does shining light on gold colloids influence aggregation?

Bhattacharya S, Narasimha S, Roy A, Banerjee S - Sci Rep (2014)

Surface plasmon resonance spectra of gold colloid of different concentrations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048914&req=5

f1: Surface plasmon resonance spectra of gold colloid of different concentrations.
Mentions: Fig. 1 describes the surface plasmon resonance band of freshly prepared gold colloidal particles of various concentrations. All spectra exhibit the absorption peak at 525 nm. Neglecting the scattering of light by small particles and using Mie's solution to Maxwell's equations for dielectric spheres in a medium one can estimate the average size (diameter d) of the particles (monomers), using the observed resonance maxima2425. The average size of the particles in all concentration of the sol is estimated to be 22 nm. The resonance energy depends on various factors, e.g., average size of the particles in the sol, surface charge on the particles, dielectric constant of the medium, etc. We observe in Fig. 1 that none of the parameters of the spectral line profile, except the intensity of the resonance peak, change with dilution. Thus, it is reasonable to believe that the dilution decreases the volume fraction of the particles in the sol, but the characteristics of the colloidal system governing the interactions between the colloidal particles, the ligand, and the medium remain unchanged.

Bottom Line: In the literature, the electrostatic interactions, van der Waals interactions, and the change in free energy due to ligand-ligand or ligand-solvent interactions are mainly considered to be the dominating factors in determining the characteristics of the gold aggregates.However, our light scattering and imaging experiments clearly indicate a distinct effect of light in the growth structure of the gold colloidal particles.We attribute this to the effect of a non-uniform distribution of the electric field in aggregated gold colloids under the influence of light.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Indian Institute of Technology Kharagpur, India.

ABSTRACT
In this article we revisit the much-studied behavior of self-assembled aggregates of gold colloidal particles. In the literature, the electrostatic interactions, van der Waals interactions, and the change in free energy due to ligand-ligand or ligand-solvent interactions are mainly considered to be the dominating factors in determining the characteristics of the gold aggregates. However, our light scattering and imaging experiments clearly indicate a distinct effect of light in the growth structure of the gold colloidal particles. We attribute this to the effect of a non-uniform distribution of the electric field in aggregated gold colloids under the influence of light.

No MeSH data available.