@article{10902/28256,
year = {2012},
month = {9},
url = {https://hdl.handle.net/10902/28256},
abstract = {This work investigates the electronic structure and photoluminescence (PL) of Co2+-doped gAl2O4 and their pressure dependence by time-resolved spectroscopy. The variations of the visible absorption band and its associated emission at 663 nm (τ = 130 ns at ambient conditions) with pressure/temperature can be explained on the basis of a configurational energy model. It provides an interpretation for both the electronic structure and the excited-state phenomena yielding photoluminescence emission and the subsequent quenching. We show that there is an excited-state crossover (ESCO) [4T1(P)↔2E(G)] at ambient pressure, which is responsible for the evolution of the emission spectrum from a broadband emission between 300 K and 100 K to a narrow-line emission at lower temperatures. Contrary to expectations from the Tanabe-Sugano diagram, instead of enhancing ESCO phenomena, pressure reduces PL and even suppresses it (PL quenching) above 6 GPa. We explain such variations in terms of pressure-induced nonradiative relaxation to lower excited states: 
2E(G)→4T1(F). The variation of PL intensity and its associated lifetime with pressure supports the proposed interpretation.},
organization = {Financial support from the Spanish Ministerio de Economia y Competitividad (Project No. MAT2011-28868-C02-01) and MALTA INGENIO-CONSOLIDER 2010 (Ref. CDS2007-0045) is acknowledged. L.N. thanks the University of
Cantabria for a postdoctoral fellowship grant.},
publisher = {American Physical Society},
publisher = {Physical Review B - Condensed Matter and Materials Physics, 2012, 86(12), 125123},
title = {Pressure-induced Co2+ photoluminescence quenching in MgAl2O4},
author = {Nataf, Lucie and Rodríguez González, Fernando and Valiente Barroso, Rafael},
}