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The theory of Aden and Kerker is used to compute the resonant response of large layered spheres to an incident linearly polarized plane wave. Cases considered include hollow spheres and those with transparent and absorbing cores whose diameters range from zero up to that of the particle. Both core and layer resonances are studied. The results are presented as partial wave amplitudes, energy densities, and scattered light intensities for a typical resonant mode, TE(39).

Single, highly charged droplets of dioctylphthalate and sulphuric acid of radius between 1 and 10 μm are suspended in vacuum in a quadrupol trap. As the droplets evaporate their radius is monitored continuously by light scattering and their charge is determined periodically by weight balancing. The droplets break when the electric stress exceeds that of surface tension. The largest fragment remains trapped allowing a determination of the change in volume and charge. The fraction of volume and charge lost is found to be independent of particle size and sign of charge and is variable. The oil drops lose (15.0 ± 3.9)% of their charge on breakup and (2.25 ± 0.96)% of their mass. The acid droplets lose (49.4 ± 8.3)% of their charge and less than 0.1% of their mass. The acid results are compared with those from a model of field emission based upon prolate spheroid deformation and the formation of Taylor cones. For both oil and acid droplets the stability limits are in agreement with those predicted by Lord Rayleigh.

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Experimental elastic-scattering characteristics of layered microspheres are reported. Single particles consisting of glass cores coated with glycerine are suspended in an evacuated quadrupole trap, and scattered light intensity is measured at a fixed angle as the glycerine evaporates. The results are compared with those calculated for concentric spheres using the Mie theory. Excellent agreement is obtained for glycerine layers of thickness less than 700 nm. For thicker layers, differences occur that are attributed to the effect of gravity on particle structure.