Luminescence decay of Ce-doped GSO under excitation of VUV photons with energy less than 30 eV at room temperature

The VUV excited decay curves for the 420 nm emission band of Ce3+ in Ce-doped gadolinium oxyorthosilicate Gd2SiO5 excited in the valence band were measured for the Ce3+ concentration of 0.5 mol%. The observed luminescence decays have the build-up and decay, which depend on the photon energy hν. The apparent decay time is 58 ns just above the band gap energy of 6.2 eV and increases to the maximum value of 92 ns at hν=7.0 eV and then decreases to 60 ns at hν=10.0 eV. For 10.0 eV<hν<30.0 eV, it tends to 60 ns. The maximum rise time is observed at hν=7.0 eV. Those results are interpreted in terms of the excitation from the ground 8S7/2 state of Gd3+ ion into the higher excited multiplets of 6.27-7.41 eV and form the valence band into the conduction band. Based on this observation, the scintillation processes in Ce-doped GSO are proposed