Measuring the size of individual particles from three-dimensional imaging experiments

Area of Science:

• Colloid and interface science
• Materials science
• Statistical physics

Background:

• Particulate samples often exhibit polydispersity (4-10%) impacting experimental outcomes.
• Individual particle size effects in dense samples are challenging to ascertain due to imaging limitations.

Purpose of the Study:

• To develop and validate a novel method for estimating individual particle radii from 3D positional data.
• To apply this method to experimental colloidal suspension data for in situ size distribution recovery.
• To investigate the relationship between particle size distribution and colloidal crystal nucleation.

Main Methods:

• Utilized 3D particle position data from simulations and confocal microscopy of colloidal suspensions.
• Developed an algorithm to estimate individual particle radii from positional information.
• Analyzed particle size distributions and correlated them with nucleation events.

Main Results:

• Successfully validated the particle size estimation method using simulations.
• Recovered the complete particle size distribution in situ from experimental data.
• Demonstrated that homogeneous colloidal crystal nucleation preferentially occurs in regions with lower polydispersity (more monodisperse).

Conclusions:

• The proposed method accurately estimates individual particle radii in dense colloidal systems.
• In situ particle size analysis provides crucial insights into sample heterogeneity.
• Reduced polydispersity in localized regions is a key factor promoting colloidal crystal nucleation.