Cooperative radiative and nonradiative effects in K2NaScF6 codoped with V3+ and Er3+.
K2NaScF6 crystals codoped with V3+ and Er3+ exhibit some novel cooperative near-IR to visible upconversion processes at cryogenic temperatures. V3+ mainly acts as a broadband sensitizer. The V3+ 3T1g --> 3T2g excitation between 13,500 and 15,500 cm(-1), after fast relaxation to V3+ 1T2g, can be transferred to Er3+ 4I(11/2), and then upconversion takes place. Four upconversion mechanisms are identified and characterized. For narrow-band laser excitation the overall efficiency of the upconversion processes is low. However, at 12 K for broadband excitation, such as in a lamp, between 12,000 and 14,500 cm(-1) the number of emitted visible photons is roughly doubled by codoping V3+ in addition to Er3+.
Departement fur Chemie und Biochemie, Universitat Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland.
Christine
C
Reinhard
Karl
K
Kramer
Daniel A
DA
Biner
Hans U
HU
Gudel
D004871:Erbium / Q000737:chemistry* / Q000528:radiation effects; D018499:Linear Energy Transfer; D008903:Minerals / Q000737:chemistry* / Q000528:radiation effects; D011829:Radiation Dosage; D014639:Vanadium / Q000737:chemistry* / Q000528:radiation effects
D008903:Minerals; D014639:Vanadium; D004871:Erbium