ULTRAVIOLET EMISSIONS FROM GD3-TRANSFER FROM PAIRS OF PHOTOEXCITED ER3+ IONS - UP-CONVERSION LUMINESCENCE FROM CSMGCL3 CRYSTALS DOPED WITH GD3+ AND ER3+( IONS EXCITED BY ENERGY)

Crystals Of CSMgCl3 containing Gd3+ and Er3+ exhibit UV emissions from excited Gd3+ ions when the 4S3/2(E) (546-nm) and the 2H11/2(F) (522-n m) states of Er3+ are pumped by pulsed laser excitation. The Gd3+ long -lived emissions that appear at 281 nm (tau = 6 ms) and 313 nm (7 = 3 ms) are assigned to the 6I7/2(C) and the 6P7/2(A) states, respectively . The luminescence dynamics indicate that the excited Gd3+ ions are pr oduced by cooperative energy transfer from excited pairs of Er3+ ions. Direct excitation of the 4G9/2(T) state of Er3+ at 277 nm is shown to sensitize the Gd3+ emission at 281 nm. Excitation spectra that are ob served when pumping the Er3+ states while monitoring the Gd3+ emission s indicate that there are spectroscopically distinct Er3+-Gd3+ cluster s with slightly different absorption energies and noticeably different emission dynamics.