Dynamic processes in single liquid microspheres

The main thrust of this research was to quantitatively follow a chemical process within a single liquid microsphere by Raman spectroscopy. Single charged microdroplets were suspended in an electrodynamic balance and elastic and inelastic light scattering techniques were used to measure their size and chemical composition. Raman spectroscopy is a non-invasive light scattering technique that has shown promise in the chemical analysis of the small sample sizes of single aerosol particles. However, the spectroscopic signal is complicated by the elastic light scattering phenomenon of morphological resonances. These resonances occur when the size and refractive index of a microsphere are such that the particle acts as an optical resonance cavity. The effect of the resonances on the Raman signal of a chemically changing microsphere was studied.; Models were developed for the calculation of the composition and temperature profiles within a droplet as it reacts with a component in the surrounding gas. The change in mass of a phosphoric acid microdroplet reacting with ammonia gas and the onset of crystallization of the ammonium phosphate product predicted by the model were compared to gravimetric data collected in an electrodynamic balance. The formulation of a shell of precipitated TiO{dollar}sb2,{dollar} the product of the reaction between a droplet titanium tetraethoxide and water vapor, was also followed by elastic light scattering techniques and further confirms the results of the model. The temperatures achieved in the highly exothermic reaction between SO{dollar}sb3{dollar} gas and a droplet of 1-octadecene were calculated through the application of the model.; The morphological resonances in the Raman signal are explained in data collected from the evaporation of droplet of a binary liquid mixture of 1-bromotetradecane and 1-iodododecane. Droplet evaporation theory and estimates of the vapor-liquid equilibrium at the surface of the droplet were combined with Raman light scattering theory to explain fine details in the data.