PCS was used on small polystyrene spheres of radius (53.5 ± 2)nm in a water solution, to measure
the sphere’s radius experimentally. A He-Ne laser was used and shone through a vial containing the
spheres. A PMT was at an angle of 90 to catch light scattered off of the spheres. Due to the small
size of the spheres when compared to the wavelength generated by the He-Ne laser (632.58 nm),
Rayleigh Scattering was used. A computer program recorded the intensity values from the PMT
and saved them for later review. Autocorrelation was used on this stochastic data set to relate it to
the underlying mechanism. After fitting an exponential to multiple trails of varying concentration,
an average error of 1.8% was found with a minimum error of 0.5% and a maximum error of 3.1%.
No measured values were outside one standard deviation from the known value of the spheres.
Measuring the hydrodynamic radius of polystyrene spheres in water
