Resolving the charging paradox of neat oil droplets in water

The thesis covers the series of questions regarding the molecular structure and charge of oil nanodroplets in water. This work proposes a mechanism responsible for the stabilization of oil nanodroplets in water, which does not involve OH- adsorption. First, it describes a numerical model for absorptive processes in sum frequency scattering (SFS) experiments on nanoobjects in absorptive media. The developed approach made it possible to analyze the O-D stretch region of SFS spectra for oil droplets in D2O. With this analytical tool, the isotopic dilution of water revealed the uncoupled O-D stretch spectrum with characteristics of a stronger hydrogen bonding network compared to the bulk. Additionally, these SFS experiments revealed a broad distribution of non-hydrogen bonded modes that were red shifted and broadened compared to similar species found previously at the air/water interface. Furthermore, a polarimetric analysis of SFS spectra demonstrated that charge transfer at the oil/water interface may be responsible for stabilization of bare oil droplets in water. Finally, complimentary second harmonic scattering measurements provided further evidence that OH- adsorption can not be responsible for negative charge at the droplet's surface and an alternative mechanism was proposed, which involved charge transfer and the high conductivity of OH- ions.