Particle size determination: An undergraduate lab in Mie scattering

Abstract

A technique for determining the size of microscopic spherical particles using light scattering is presented as an undergraduate physics lab. Scatterer size is determined from angular scattering distribution measurements of laser light scattered from a dilute suspension of latex spheres with diameters of 4.99Ϯ0.05 and 6.038Ϯ0.045 m. Previous experiments of this type used approximate theoretical corrections and required the construction of specialized sample cells to minimize complicating effects. As a significant improvement to these, we generate angular scattering distributions from Mie theory and, using an accurate numerical procedure, correct these distributions for Snell's law and foreshortening effects. Scatterer size is then determined using a fast, robust fitting algorithm to compare these corrected angular scattering distributions to measured angular scattering distributions. We fit the scatter from a solution of 6.04-m-diam spheres to spheres of 5.95Ϯ0.11 m diameter, and that from a solution of 4.99-m spheres to 4.85 Ϯ0.15 m. Additionally, scattering data for a 2:1 mixture of spheres of diameters 4.99 and 6.04 m are taken, and after numerical adjustment for Snell's law and foreshortening effects, good agreement with theory is obtained.

Using ultrasonic atomization to produce an aerosol of micron-scale particles

“…27 Data sets such as the one shown in Fig. 3͑a͒ were numerically fit with the help of a modified version of the FORTRAN MIEV0 program.…”

Dual wavelength multiple-angle light scattering system for cryptosporidium detection

“…Light scattering techniques are widely used to investigate the particle properties such as such as size [14][15][16] , refractive index [17][18] and concentration [19][20] and also applied to biological particle detection [21][22][23][24][25][26] as its advantages; easy to perform; low maintenance; non-invasive; have high sensitivity; and the potential for real-time detection.…”

High concentration measurement of mixed particle suspensions using simple multi-angle light scattering system

“…For suspension in high concentration, multiple scattering effects are significant causing the scattered signals to vary in indirect proportion to the particle concentration 6 . As the light scattering intensity is determined by the properties of the scattering particles as per equation 2, light scattering techniques have been applied to obtain the scattering phase function to infer the particle's size [7][8][9] , refractive index [10][11] , and concentration [12][13] . However, there are some limitations of measurement for particle suspension at high concentration due to multiple scattering effects [14][15] .…”