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Highly supersaturated electrolyte solutions can be prepared and studied employing an electrodynamic levitator trap (ELT) technique. The ELT technique involves containerless suspension of a microdroplet thus eliminating dust, dirt, and container walls which normally cause heterogeneous nucleation. This allows very high supersaturations to be achieved. A theoretical study of the experimental results obtained for the water activity in microdroplets of various electrolyte solutions is based on the development of the Cahn-Hilliard formalism for electrolyte solutions. In the approach suggested the metastable state for electrolyte solutions is described in terms of the conserved order parameter to (r,t)

We show experimentally that the positional uncertainty in long-term images of a microparticle in a Paul trap in air can be reduced to the optical limit, and below the pseudopotential limit. For this damped system, far below any Mathieu instability, the particle’s thermally induced positional noise is extremely sensitive to the phase of the driving field. Accumulating images strobed at the proper phase produces a long-term optical image which is essentially free of thermally induced positional noise. Although noise squeezing theory does not apply at such large dissipation, our results may be understood through recent theory of the Brownian parametric oscillator. Use of this theory coupled with our observations suggests that the extreme reduction in spatial variance observed by using our technique results from working in a low Reynolds number regime.

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