Particle sizing in strongly turbid suspensions with the one-beam cross-correlation dynamic light-scattering technique

Area of Science:

• Colloid and Surface Science
• Optical Physics
• Materials Science

Background:

• Particle sizing in turbid suspensions is crucial for various scientific and industrial applications.
• Traditional one-beam cross-correlation dynamic light scattering (DLS) systems struggle with low signal-to-baseline ratios in highly turbid media.
• This limitation hinders accurate characterization of small particles in concentrated or opaque suspensions.

Purpose of the Study:

• To improve the signal-to-baseline ratio of a one-beam cross-correlation DLS system.
• To enable reliable sizing of small particles in strongly turbid suspensions.
• To enhance the applicability of DLS for characterizing challenging sample types.

Main Methods:

• Implemented a square cross-sectional sample cell to reduce light attenuation and scattering.
• Introduced a 200-microm-wide slit to filter out weak single and strong multiple scattering.
• Optimized detector field of view alignment to focus on the strongest single scattering region.
• Utilized polystyrene latex spheres (65-562 nm diameter) in aqueous suspensions for testing.

Main Results:

• Achieved a signal-to-baseline ratio comparable to other DLS systems.
• Successfully sized polystyrene latex spheres with diameters ranging from 65 to 562 nm.
• Obtained measurements with better than +/-10% accuracy for radius determination.
• Demonstrated reliable performance for volume fractions up to a few percent.

Conclusions:

• The described optical and sample cell improvements significantly enhance one-beam DLS performance in turbid suspensions.
• This optimized system provides accurate and rapid particle sizing for a range of small particles.
• The enhanced system broadens the utility of DLS for characterizing difficult-to-measure colloidal systems.