Characterization of Non-spherical Nanoparticles Using Scattering Techniques

Abstract

This thesis employs dynamic light scattering (DLS), depolarised dynamic light scattering (DDLS), and small angle X-ray scattering (SAXS) for the precise characterization of suspensions of nanoparticles of different sizes and shapes. The first study examines several types of nanodiamonds, specifically detonation nanodiamonds (DNDs) and three types of high-pressure high-temperature nanodiamonds (HPHT NDs). Due to the characteristics of the nanodiamonds, the analysis using the three techniques was generally uncomplicated. For DLS, both the exponential fit method and size distribution analysis were used. However, DLS analysis assumes spherical particles, which was not the case for all particles. Therefore DDLS was used to extract translational and rotational diffusion coefficients, and the dimensions of the nanodiamonds were determined from the DDLS results using theoretical models that relate diffusion rates to the dimensions. For SAXS analysis, SasView software was used to analyse the data for different shapes of particles like spheres and cylinders. Overall, very good results were obtained from the combination of the three techniques to characterize the nanodiamonds. The second study examined different shapes and sizes of metallic nanoparticles by following the protocols described above. The four particles were gold nanospheres, gold nanorods, silver nanoplates and silver nanocubes. Due to the optical properties of metal nanoparticles, the data analysis was more complicated. However, the combination of the three techniques provided results that are consistent with the manufacturer's description. Overall this work has shown that combining these three techniques provides robust characterisation of non-spherical particles in suspension