COLORED MULTILAYERS FROM TRANSPARENT SUBMICROMETER SPHERES

Ordered multilayers were formed by evaporating the water from polystyrene latex suspensions containing monodisperse spherical particles of diameter smaller than the wavelength of visible light. It was found that multilayers of different thicknesses exhibit different intensive and uniform colors when illuminated with polychromatic light. Their intensity strongly depends on the refractive index of the substrate on which the multilayers are deposited. The colors are due to interference at plane parallel films of different thicknesses. By measuring the wavelengths at which the reflectance of two neighboring multilayers coincide, it is established that the particle array has hexagonal packing. This is in agreement with the data obtained by scanning electron microscopy and atomic force microscopy. Such an ordered multilayer exhibits a stepwise change in its color each time when the upper particle layer is removed. This property could find application for creating and recording color images.