Hydrogen-bond dynamics in 1-propanol and glycerol mixtures in the pressure and temperature dimensions

In this experiment, we shall investigate the dynamics of the hydrogen bond in 1-propanol and propanol-glycerol mixtures under pressure and temperature variation. Neutrons are our only option because techniques like dynamic light scattering and dielectric spectroscopy can't clearly differentiate the contributions from various sample components. We deuterate the sample in order to study the dynamics of the carbon backbone vs. hydrogen bond network since neutrons have a contrast in the density of their scattering lengths for different elements. By creating two different types of samples, one with deuterated propanol and a deuterated combination (propanol-glycerol), and the other entirely protonated, separation can be accomplished. Incoherent scattering will predominate for the protonated component, and the dynamics of that component will be apparent in the data. In order to determine how closely the dynamics of the individual components resemble those of the global alpha relaxation, we shall perform simultaneous dielectric spectroscopy. We will analyze the obtained data to extract the timescales and Q-dependence of the associated dynamics, focusing on the effect of increased pressure.

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