EXCITED-STATE ABSORPTION BY EU-2+ IN NAF AND KMGF3

Excited-state absorption (ESA) has been studied in NaF:Eu2+ and KMgF3:Eu2+ using a pump-probe technique in the visible region. The pump fluence dependence of fluorescence and transmission gives evidence of ESA in the ultraviolet. A broad ESA band is observed at wavelengths shorter than about 600 nm in NaF:Eu. Comparison of this result with earlier data on KBr:Eu, KCl:Eu, and NaCl:Eu, and with published photoconductivity data suggests that the ESA is due to photoionization, despite disagreement with the predictions of an electrostatic model for ionization. In KMgF3:Eu no ESA is evident in the visible, but strong ESA is observed at the 193-nm pump wavelength. © 1990 The American Physical Society.