Laser induced Fano scattering, electron–phonon coupling, bond length and phonon lifetime changes in α-Fe2O3 nanostructures

Abstract

We have extensively studied the laser-induced Fano scattering, electron–phonon coupling, bond length and phonon lifetime of the α-Fe₂O₃ nanostructure prepared through a simple co-precipitation method. A noticeable red shift and asymmetry have been observed in the phonon modes of the prepared α-Fe₂O₃ nanostructure. The traditional assessment of asymmetric broadening and a red shift in the Raman spectra of a nanomaterial was due to the quantum confinement effect. In the present investigation, the red shift and the asymmetry in the phonon modes of the α-Fe₂O₃ nanostructure have been studied on the basis of the heating effect and Fano interference between the discrete phonon and the laser-induced electron plasma in the nanomaterial. The observed asymmetrical factors of the A_1g(1) and E_g(4) phonon modes were positive and negative respectively and are seen to be decreasing with the laser power. The laser-induced surface temperature of the material has been studied using the Stokes/anti-Stokes method. The bond lengths of the Fe–O molecules present in the α-Fe₂O₃ nanomaterial increased and the calculated Fröhlich interactions decreased with the laser energy.