2.2.4. Raman Spectroscopy

Raman spectra were collected on powder samples at room temperature in back-scattering geometry using an inVia Renishaw 1000 spectrometer equipped with an air-cooled, charge-coupled device (CCD) detector and edge filters. A 488.0 nm emission line from an Ar<sup>+</sup> laser was focused on the sample using a Leica DLML microscope with 5 × or 20 × objectives and an incident beam power of about 5 mW. A solid-state laser emitting at 785 nm with low power to avoid sample damage (about 2 mW) was used to analyze the 10Fe10CoSiO<sup>2</sup> catalyst. The spectra were calibrated using the 520.5 cm−<sup>1</sup> line of a silicon wafer. The spectral resolution was 3 cm−<sup>1</sup> . Data analyses included baseline removal and curve fitting

using the Gauss Lorentzian cross-product function in the Peakfit 4.12 software (Systat Software Inc., San Jose, CA, USA, 2007).
