High-pressure studies of the near-infrared; fluorescence of Cr4+:yttri
um aluminum garnet (YAG) at 40 K have been used to induce a T-3(2)-E-1
crossover above 200 kbar and have permitted the observation of E-1-->
(3)A(2) emission. The E-1-->(3)A(2) emission band is narrow, occurs ne
ar 1100 nm, and shows a small redshift expected for a spin-flip transi
tion. The energy of the emission is similar for different Cr4+ centers
present in YAG; A preliminary lifetime measurement of the E-1-->(3)A(
2) emission of the principle Cr4+ Site at similar to 270 kbar and 40 K
yields a value of similar to 250 mu s, and an similar to eightfold in
crease relative to the value at ambient pressure and 40 K.