Raman study of ionic water-based copper and zinc ferrite magnetic fluids

Raman spectroscopy is used to investigate the OH-bending and OH-stretching modes of chemisorbed OH-groups in copper-ferrite and zinc-ferrite water-bas ed magnetic fluid samples. Room-temperature Raman spectra were taken from d iluted magnetic fluid samples and compared with the spectrum taken from liq uid water. The suppression of the symmetric OH-stretching Raman modes from the ionic magnetic fluid sample spectra is discussed in terms of the replac ement of a hydrogen atom from the water molecule by the nanoparticle surfac e. Moreover, changes on the area ratio between hydrogen bonded and nonhydro gen bonded OH-Raman peaks in the ionic magnetic fluid samples, as compared to the OH-Raman peaks from liquid water, are discussed in terms of changes on the hydrogen bond strength. (C) 1999 Elsevier Science B.V. All rights re served.