Rayleigh, Mie, and Tyndall scatterings of polystyrene microspheres in water: Wavelength, size, and angle dependences

The wavelength-, size-, and angle-dependent light scattering properties of polystyrene microspheres dispersed in water are systematically investigated in a spectral range from 300 to 1300 nm and a sphere-diameter range from 20 nm to 85 mu m. According to the wavelength dependence of the scattering cross section on the value of delta=lambda(1)/2r, where lambda(1) and 2r are the wavelength in the surrounding medium and the diameter of the microsphere, the light scattering behaviors can be roughly classified by three major categories. Under our considered conditions, when delta >= 10, it is termed Rayleigh scattering, characterized by a minus fourth-power dependence on the wavelength; when 10(-2)<=delta <= 10, it is termed Mie scattering, characterized by a power factor varying within a range roughly -4 to +2; finally when delta <= 10(-2), it is termed Tyndall scattering, characterized by an almost constant scattering cross section that is actually independent of the wavelength. All of our experimental results on 16 scattering samples of different sizes are in good agreement with the theoretical predictions within an experimental uncertainty of +/- 5%.