Quasielastic neutron scattering by concentrated aqueous "single-nano buckydiamond" dispersion

TL;DR

This study investigates the diffusion behavior of aqueous dispersions of single-nano buckydiamond particles using quasielastic neutron scattering, revealing hydration water with reduced mobility around the particles.

Contribution

It introduces two analytical approaches to quantify hydration water in nano-diamond dispersions and characterizes its diffusive properties.

Findings

Hydration water constitutes about 3% of the dispersion.

Hydration water exhibits retarded diffusion compared to bulk water.

The analysis methods effectively distinguish hydration water from bulk water.

Abstract

The diffusion characteristics of stable aqueous dispersion of "single-nano buckydiamond" concentration 80 mg/ml, average particle size 8 nm and pure water as the reference system were investigated by quasielastic neutron scattering. The difference of these spectra were analyzed by two ways. In the first way dispersion water was described as the two-component system, consisted of bulk water and a small additive having presumably the lorentzian form (Hydration water, HW). This additive is located in the nearest surrounding of nano-diamond particle. The second approach included the direct subtraction of dispersion water and bulk water spectra, properly normalized in the regions of their wings, where the influence of HW can be neglected. For both cases of analysis, the relative fraction HW appeared to be about 3%. HW was found to have diffusive mobility which is retarded as compared to bulk water due to the weakening of the rotational component of diffusion and the increased residence lifetime of molecules.