NMR measurements of self-diffusion coefficients of degassed water

Abstract

In this project I have measured the molecular self-diffusion coefficient of water in order to quantify the effects of dissolved gas concentration upon self-diffusion. It has been shown that degassing water samples has enhanced the stability of oil-in- water emulsions formed without the aid of stabilizers such as surfactants and polymers 1. Degassing enhances water's ability to work as a solvent of non-polar molecules. There are electrical conductivity changes in the water when it is completely degassed; such a change demonstrates that there is a change in molecular structure. This leads to an interest in the self-diffusion behaviour of the water under these conditions2. The project began with optimization of the phase cycling scheme for the NMR Cotts-13 interval sequence, which measures self-diffusion in the presence of local magnetic field inhomogeneity. This technique development allowed us to measure the self-diffusion coefficient of the water samples that are degassed and non-degassed.