title: Spectroscopic properties and location of the Tb(3+) and Eu(3+) energy levels in Y2O2S under high hydrostatic pressure.
abstract: In this contribution, an extensive spectroscopic study of Y2O2S doped with Eu(3+) and Tb(3+) is presented. Steady-state luminescence and luminescence excitation spectra as well as the time-resolved spectra and luminescence kinetics were obtained at high hydrostatic pressures up to 240 kbar. It was found that pressure quenches the luminescence from the (5)D3 excited state of Tb(3+) and recovers additional luminescence related to transitions from the (5)D3 state of Eu(3+). These effects are related to the pressure-induced increases in the energies of the ground electronic manifold 4f(n) of Eu(3+) and Tb(3+) ions with respect to the band edges. Analysis of the emission and excitation spectra allowed the estimation of the energies of the ground states of all lanthanide (Ln) ions (Ln(3+) and Ln(2+)) with respect to the valence and conduction bands edges of the Y2O2S host. The bandgap energy and difference between energies of the ground states of Ln(2+) and Ln(3+) have been calculated as functions of pressure. The experimental high-pressure spectroscopy results allow the calculation of the absolute values (calculated with respect to the vacuum level) of the energies and pressure-induced shifts of the conduction and valence band edges and the ground states of Ln(3+) and Ln(2+) ions in Y2O2S.
authors.affiliation: Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, 80-308 Gdańsk, Poland. s.mahlik@ug.edu.pl fizmgr@ug.edu.pl.
authors.forename: M
authors.initials: M
authors.lastname: Behrendt
authors.affiliation: Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, 80-308 Gdańsk, Poland. s.mahlik@ug.edu.pl fizmgr@ug.edu.pl.
authors.forename: S
authors.initials: S
authors.lastname: Mahlik
authors.affiliation: Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, 80-308 Gdańsk, Poland. s.mahlik@ug.edu.pl fizmgr@ug.edu.pl.
authors.forename: K
authors.initials: K
authors.lastname: Szczodrowski
authors.affiliation: Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, 80-308 Gdańsk, Poland. s.mahlik@ug.edu.pl fizmgr@ug.edu.pl.
authors.forename: B
authors.initials: B
authors.lastname: Kukliński
authors.affiliation: Institute of Experimental Physics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, 80-308 Gdańsk, Poland. s.mahlik@ug.edu.pl fizmgr@ug.edu.pl.
authors.forename: M
authors.initials: M
authors.lastname: Grinberg