Abstracts 1999

Abstract of Publication No. 337

Markus Wermuth and Hans U. Güdel
Photon Avalanche in Cs2ZrBr6:Os4+
J. Am. Chem. Soc. 121, 10102-10111 (1999)      Full Text (PDF)      DOI-Link     

Abstract: The 15 K visible (VIS) upconversion-luminescence of Cs2ZrBr6:0.2% Os4+ upon excitation in the near-infrared (NIR) is presented and analyzed. Crystals of Cs2ZrBr6:0.2% Os4+ were synthesized and grown by the Bridgman technique. At 15 K VIS luminescence around 16000 cm1 is induced by NIR excitation around 11400 and 13400 cm1. Due to the low maximum vibrational energy of 220 cm1, four excited states participate in the upconversion processes. A photon avalanche and a ground-state absorption/excited-state absorption sequence are identified as upconversion mechanisms by high-resolution upconversion-excitation spectra and by power-dependent and time-resolved measurements. The lifetimes of the excited states G4 (3T1g), G5 (3T1g), G5 (1T2g), and G1 (1A1g) at 15 K are 45 ms, 1.6 ms, 261 ms, and 8 ms, respectively. The dynamics of the upconversion are simulated with a rate-equation model.

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