UP-CONVERSION MECHANISMS IN ER3-DOPED BA2YCL7()

Efficient near infrared to visible upconversion luminescence is report ed in the low phonon-energy host material Ba2YCl7:x% Er3+ (x=1, 10, 10 0). The upconversion mechanisms upon I-4(9/2) excitation (approximate to 800 nm) are investigated by means of excitation and time-resolved l uminescence spectroscopy. H-2(9/2) is found to be populated by energy transfer upconversion and excited-state absorption, depending on the e xcitation energy. Characteristic excited-state absorption peaks in the excitation spectra a are used as a fingerprint to determine the popul ation mechanisms for the other states with high luminescence intensiti es: S-4(3/2)/H-2(11/2), F-4(9/2), and (4)G(11/2). The assignment is co nfirmed by temperature, concentration, power, and time-dependent measu rements. The relative intensities are accounted for by a Judd-Ofelt an alysis.