Weak-localization effect in Fano asymmetry of C implanted rutile TiO2 nanostructure

Fano resonance is the degree of asymmetry that describes the interference of continuum states with discrete states and causes asymmetric line shape in the optical response. The hydrothermally synthesized TiO 2 nanostructures in this work are doped with 1.5 MeV carbon (C) ion beams to explore the Fano effect via the asymmetry in the Raman spectra. It is observed that the E g and A 1 g modes are asymmetric toward the lower wavenumber. The Fano effect is responsible for the peak asymmetry, which rises with C ion fluence. The Breit-Wigner-Fano line shape fits well the E g and A 1 g modes. The calculated asymmetry parameter (1/q) for implanted TiO 2 nanostructures represents weakly localized asymmetry with temperature. The electron-phonon coupling strength grows with the C ion fluence. The effects of temperature and defect level on the asymmetry parameter are also discussed.