The most powerful tool for the structural analysis of tungsten suboxide nanowires: Raman spectroscopy

Crystalline tungsten suboxide nanowires were grown on silicon substrates by thermal evaporation of tungsten powder in a flow of argon gas without any catalyst. With different growth temperatures, two kinds of tungsten suboxide nanowires (W₁₈O₄₉ and W₂₀O₅₈) were obtained. The structures, morphologies, and compositions of these two nanowires were characterized by scanning electron microscopy (SEM), electron probe microanalyzer (EPMA), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS), and Raman techniques. The results show that XRD and TEM are not good characterization techniques for identifying W₁₈O₄₉ and W₂₀O₅₈ nanowires; however, Raman spectroscopy (RS) is a powerful tool to distinguish the difference between them. This is due to the notable molecular bond contributing to the vibrational frequency.