Ultrafast pump-probe spectroscopy studies of CeO2 thin film deposited on Ni-W substrate by RF magnetron sputtering

Abstract This study presents the first investigation of rapid dynamical processes that occur in pure CeO 2 thin film, using ultra fast pump-probe spectroscopy at room temperature. For this purpose we have used a single (200) oriented CeO 2 film deposited on biaxially textured Ni-W substrate by RF magnetron sputtering technique. The ultrafast transient spectra show initial sharp rise transition followed by an exponential photon decay. This rise time is about 10 ps irrespective of the probe wavelengths range 500–800 nm. The initial decay constant (τ) at 500 nm probe wavelength is found to be 171 ps, while at 800 nm probe wavelength it is 107.5 ps. The ultrafast absorption spectra show two absorption peaks at 745 and 800 nm, and are attributed to the electronic transitions from 2 F 7/2 – 2 F 5/2 and 1 S 0 – 1 F 3 respectively. The relatively high intensity absorption peak at 745 nm indicates dominant f – f electronic transition. Further, the absorption peak at 745 nm splits into two distinct peaks with respect to delay time, and is attributed to the charge transfer in between Ce 4+ and Ce 3+ ions. These results indicate that CeO 2 itself is a potential candidate and can be used for optical applications.