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 (W,,049 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.