Effect of laser power on force constant and phonon lifetime of stretching and bending vibration of Cu-doped WO nanostructures.

The influence of Cu-doping on their structural, vibrational and morphological properties of hydrothermally prepared Cu-doped WO has been studied. X-ray Diffraction studies confirm the tetragonal structure of WO and lower angle shift in doped samples indicates the incorporation of Cu in tungsten sites. Field emission scanning electron microscopy (FESEM) images exhibit micro rod-like morphology of the as-synthesized WO materials shows microstructure with rod-like projections slowly changes into nanorods and plates for doped samples. The absorption peak of pure and Cu-doped WO occurs in the region of 200 to 350 nm and centered at 314 nm. In Raman spectra, prominent peaks of WO have appeared at 676 and 810 cm which represent the stretching mode of υ (OWO). Peak around 240 cm represents the bending vibration of υ (WOW). Another peak at 322 cm is the deformation mode δ (OWO). Force constant of the prepared samples has been calculated from the blue shift obtained in both stretching and bending vibrational mode by varying laser power from 0.045 to 11.25 mW. Phonon lifetime has been calculated by deconvoluting the peaks using Lorentzian function.