Study of the interactions between the surface chemisorbed layer and the surrounding media in magnetite-coated nanoparticles using Raman spectroscopy

Raman spectroscopy is used to investigate surface-coated magnetite nanoparticles (9 nm diameter) dispersed in aqueous medium. In a first sample, the magnetite nanoparticle is coated with dextran. In a second sample the magnetite nanoparticle is double-coated with a dodecanoic layer following an ethoxylated polyalcohol layer. The Raman measurements were focused on the typical intra-molecular OH-stretching mode chemiosorbed at the nanoparticle surface. The data are discussed in terms of the suppression of the symmetric and asymmetric hydrogen bonded mode in both samples.