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 nanopart icles (9 nm diameter) dispersed in aqueous medium. In a first sample, the m agnetite nanoparticle is coated with dextran. In a second sample the magnet ite nanoparticle, is double-coated with a dodecanoic layer following an eth oxylated polyalcohol layer. The Raman measurements were focused on the typi cal intra-molecular OH-stretching mode chemiosorbed at the nanoparticle sur face. The data are discussed in terms of the suppression of the symmetric a nd asymmetric hydrogen bonded mode in both samples. (C) 2001 Elsevier Scien ce B.V. All rights reserved.