Photon-correlation spectroscopy for small spherical inclusions in a micrometer-sized electrodynamically levitated droplet

Micrometer-sized droplets of saturated sodium chloride solution were captured in an electrodynamic levitator and maintained at constant diameter for several days at a time. Both pure droplets and droplets containing 0.5-μm subparticles (guests) were studied by means of 90-deg scattering of polarized laser light. Analysis of the correlation function for the intensity of the scattered light gave characteristic decay times of −9 ms, which has a good correspondence with the physical parameters of the solution and the size of the subparticles. Longer characteristic times are measures of morphological features of the electromagnetic field intensity in the host particles. A new phenomenon was observed when the exit polarizer was crossed to the input polarization. Scattered light corresponding to light from the guest particles could only be visualized from a shell near the exterior of the sphere and not from the interior of the host droplet.