EFFECT OF MPEG COATING ON MAGNETIC PROPERTIES OF IRON OXIDE NANOPARTICLES: AN ESR STUDY

摘要

Metoxy polyethylene glycol (MPEG) coated and uncoated Fe_3O_4 (SPION) nanoparticles have been investigated by Electron Spin Resonance (ESR) technique at the temperature range between 10-300K. ESR measurements on powdered samples have been carried out by using X-band ESR Bruker EMX spectrometer. A strong and broad single ESR signal has been observed at all temperatures. Temperature dependence of ESR linewidth and resonance field is studied. The linewidth increases and the resonance field decreases by decreasing temperature while the ESR signal intensity remeains almost independent on the temperature. The shift in the resonance field value is a clear indication of the induced field (exchange anisotropy field), causing the frustration (disorder) of any magnetic system. A strong effect of coating on magnetic properties of SPION nanoparticles has been observed as well.