Slavov and coworkers tested the magnetite by increasing the laser power from 0.9 to 9.0 mW. "The characteristic peak positions of magnetite (Fe3O4) and its possible oxidation byproducts, maghemite (γ-Fe2O3) and hematite (α-Fe2O3) determined the Raman region of interest" in Slavov et al. investigation. The range is 100-1200 cm -1 . "For correct assignment of the band positions … and for phase identification," Vlasov and coworkers used the following peaks (in cm -1 ): Magnetite 193 (weak), 306 (weak), 538 (weak), 668 (strong); Maghemite 350 (strong), 500 (strong), 700 (strong); Hematite 225 (strong), 247 (weak), 299 (strong), 412 (strong), 497 (weak), 613 (medium). "The analysis of all spectra reveals the destructive influence of the atmospheric oxygen on the structural stability of even coated magnetite nanoparticles. For the uncoated magnetite particles, a timeline of less than 30 days meant a total transition towards maghemite. … The oxidation process starts at a very early stage after formation of the nanoparticles" ).