@article{3036350, title = "Magnetic resonance study of γ-FeF2OF3 nanoparticles dressed in oxygen based free radicals", author = "Guskos, N. and Typek, J. and Zolnierkiewicz, G. and Wardal, K. and Guskos, A. and Berczynski, P. and Petridis, D.", journal = "Materials Science-Poland", year = "2013", volume = "31", number = "4", pages = "587-594", issn = "2083-1331, 2083-134X", doi = "10.2478/s13536-013-0143-3", keywords = "Agglomerated nanoparticles; Ferromagnetic resonance lines; Integrated intensities; Maghemite nanoparticle; Magnetic interactions; Magnetic nano-particles; Nanoparticle agglomerates; Temperature dependence, Agglomeration; Ferromagnetic resonance; Free radicals; Magnetic resonance; Oxygen, Nanoparticles", abstract = "Two composites consisting of g-FeF2OF3 (maghemite) nanoparticles covered by two different oxygen-based free radicals derived from a 4-(methylamino)phenol sulphate and 8-hydroxy-1,3,6-trisulfonic trisodium salt acid were prepared and investigated by the magnetic resonance method in the 4 - 300 K range. Both composites displayed broad and very intense ferromagnetic resonance (FMR) lines originating from g-FeF2OF3 agglomerated nanoparticles. The FMR spectrum was fitted satisfactorily at each temperature by two Landau-Lifshitz functions reflecting the existence of magnetic anisotropy in the investigated system. The temperature dependence of the obtained FMR parameters (resonance field, linewidth, integrated intensity) was studied and the results were interpreted in terms of magnetic interactions between free radicals and nanoparticle agglomerates. A comparison with previously studied similar systems containing maghemite nanoparticles was made and conclusions about the role of free radicals were drawn.© Wroclaw University of Technology." }