Asymmetric Lattice Vibrational Characteristics of Rutile TiO2 as Revealed by Laser Power Dependent Raman Spectroscopy

Titanium dioxide (TiO2) is important for both fundamental studies and technical applications. Here we present laser power dependence Raman spectroscopic studies of rutile TiO2 to reveal the response of various Raman-active lattice vibrations. Apparently, different vibrational modes display distinctive and reversible trends with the change of laser power. The Ti-O bond strength involved with different vibrational modes changes differently as the laser power changes. The relaxation time becomes shorter as the laser power increases. The changes of the bond strength and relaxation time can be related to the local temperature change with the laser power. The observed different behaviors in the vibrational modes suggest that the lattice movements along various directions face different temperature environments under the same light irradiation.