M. True

Luminescent properties of Gd2SiO5 powder doped with Eu3+ under VUV?UV excitation

The luminescent properties of Gd2SiO5 powder crystals doped with Eu3+ were investigated using synchrotron radiation and a VUV laser (157.6?nm) as excitation sources. The excitation spectra in the range of 160?330?nm monitoring the red emission from Eu3+ ions reveal bands corresponding to intraconfigurational 4f?4f transitions of Gd3+ and charge transfer states (CTS) of Eu3+?O2?, as well as interband transitions of the Gd2SiO5 host, indicating an efficient energy transfer process from the host or directly from Gd3+ to Eu3+ ions. The inspection of emission lines from Eu3+ ions suggests that there are three inequivalent sites for Eu3+ in this host. The excitation band around 215?nm and the unique emission features associated with this excitation band were attributed to one of the inequivalent Eu3+ sites, which exhibits an unusually weak coupling with host lattice. The energy levels of Eu3+ in the Gd2SiO5 host were tentatively assigned according to the laser excited emission spectra.

VUV-luminescence and excitation spectra of the heavy trivalent rare-earth ions in fluoride matrices

VUV 4fn → 4fn−15d transitions of Gd3+, Er3+, Tm3+, and Lu3+ in fluoride matrices have been analyzed with high-resolution luminescence and excitation spectroscopy. In trifluorides, strong electron-phonon coupling has been found. In the other matrices, the luminescence spectra clearly yield zero-phonon lines and phonon replica, indicating intermediate coupling. The energies of the zero-phonon lines observed are compared with theoretical predictions. Near the threshold of f → d excitations, some of the excitation spectra yield sharp structures which cannot be explained with phonon replica but will be discussed in terms of the energy levels of the 4fn−15d configuration.