We measured the optical conductivity $\tilde{\sigma }\left(\omega \right)$ spectra caused by photocarriers in anatase $\mathrm{Ti}{\mathrm{O}}_2$ by applying ultraviolet-pump terahertz-probe spectroscopy on epitaxially grown thin films. Drude model analyses of $\tilde{\sigma }\left(\omega \right)$ spectra reveal that, in the terahertz region, the reduced mass ($\widehat{m}$) of the carriers is greater and their damping constant ($\gamma$) is smaller than those in the infrared region. With regard to the extended Drude model, these differences can be attributed to the frequency dependence of $\widehat{m}$ and $\gamma$ originating from carrier-phonon scatterings. Furthermore, the interaction between carriers and Ti-O stretching modes in the $500–1000-\mathrm{c}{\mathrm{m}}^{-1}$ region strongly influences the intrinsic carrier scattering mechanism in anatase $\mathrm{Ti}{\mathrm{O}}_2$.

• Received 23 March 2015
• Revised 4 March 2016

DOI:https://doi.org/10.1103/PhysRevB.94.041113