Aggregation in colloidal gold

Journal Article · Wed Mar 01 04:00:00 EST 1989 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.39.2675· OSTI ID:6357429

Wilcoxon, J P; Martin, J E; Schaefer, D W

Static and dynamic light scattering are used to study the aggregation kinetics and structure of colloidal gold. Fast aggregation is achieved by either addition of pyridine, lowering of the pH, or addition of salt. The kinetics of rapid growth is followed by measurement of the polarized relaxation time tau/sub v//sub v/ (proportional to the mean cluster radius). We observe a power law, tau/sub v//sub v/proportional(Ct)/sup x/, with x = 0.38 +- 0.04, where t is the time and C is the initial sol concentration. Measurements of the depolarized relaxation time tau/sub v//sub h/ as Q..-->..0 (Q is the wave vector) are found to be proportional to the third power of the cluster radius, typical of rotational diffusion. Such measurements allow independent confirmation of the kinetics as tau/sub v//sub h/ = (Ct)/sup 3x/, with x = 0.38 +- 0.04. The static light scattering intensity I from these rapidly grown clusters obeys a power law, IproportionalQ/sup -//sup y/ with y = 1.74 +- 0.1, at a wavelength of lambda = 633 nm (optical resonance is 680 nm), with the value of y increasing away from resonance to a value of 2.0 +- 0.1 at lambda = 457 nm. Under diluted conditions the scattering behavior is identical on and off resonance with y = 2.0 +- 0.1.

• Research Organization: Sandia National Laboratories, Albuquerque, New Mexico 87185
• OSTI ID: 6357429
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 39:5; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AGGLOMERATION
COLLOIDS
DISPERSIONS
ELEMENTS
GOLD
GROWTH FACTORS
LIGHT SCATTERING
METALS
MITOGENS
ORGANIC COMPOUNDS
PARTICLE KINEMATICS
PARTICLES
PARTICULATES
PROBES
PROTEINS
SCATTERING
SOLS
TRANSITION ELEMENTS