Emission spectroscopy of carbon-covered iron nanoparticles in different gas atmospheres

Black body-like radiation was observed when irradiating ferrocene vapor (Fe(C5H5)(2)) in xenon, argon, helium or hydrogen atmosphere by an ArF excimer laser. The emission originated from carbon-covered iron nanoparticles excited by the laser pulses. Time-resolved spectroscopy of the thermal radiation was performed at different delay times relative to the exciting laser pulse. Particle temperatures were obtained by fitting the calibrated spectra by the Planck equation, taking the emissivity of nanoparticles into consideration. The cooling rates of the nanoparticles and the lifetime of the thermal radiation were determined in the total pressure region of 0.2-50 mbar for the different gas atmospheres. Based on the measured values, accommodation coefficients and deexcitation cross-sections were obtained. These data characterise the inelastic interaction between the nanoparticles and the surrounding gas atmosphere. The iron phase dependence on the cooling rate was examined by X-ray diffraction of nanoparticle film deposits. (C) 2002 Elsevier Science B.V. All rights reserved.