Fluorescence properties of Fe nanoparticles prepared by electro-explosion of wires

A novel electro-exploding wire technique has been employed to synthesize pure Fe nanoparticles. The Fe nanoparticles exist in a body-centered cubic (bcc) phase with an average size of the particles in the range ∼17 nm. A weak feature at ∼352 nm in the UV-vis absorption spectra has been established to be remnants of a surface plasmon peak, broadened due to the reduced particle size. Further, a fluorescence emission peak is observed at ∼303 nm for excitation wavelength in two different ranges, 220-250 nm and 255-280 nm. The position of the fluorescence peak remains fixed, irrespective of the excitation's wavelength employed. The fluorescence is assigned to electronic transitions from excited states to d levels of the Fe nanoparticles. In concomitant with these, two resonant absorptions are observed at 224 nm and 270 nm, evident from the fluorescence excitation spectra which allow us to give a description of the electronic levels operating in this system