Figure 4: Luminescence time-resolved spectra at 77 K. The initial curve is obtained after laser pulse, and the following curves were obtained with different steps, as indicated: (a) undoped TiO₂ excited at 337 nm, step of 20 ns; (b) TiO₂-0.1CdS excited at 337 nm, step of 20 ns; (c) pure CdS excited at 337 nm, step of 100 ns; (d) TiO₂-0.1CdS excited at 410 nm, step of 100 ns; (e) pure CdS excited at 410 nm, step of 100 ns; (f) superposition of the normalized emission spectra obtained immediately after the laser pulse for the TiO₂-0.1CdS sample and pure CdS both excited at 410 nm.