The effect of pressure on the emission spectra of Tm3+:YAG and Cr3+:Tm
3+:YAG was studied. Shifts in emission peaks ranging from -0.14 to 0.5
4 angstrom/kbar were observed in Tm3+:YAG. The ability of pressure to
resolve competing absorption of overlapping Cr3+ (4T1) and Tm3+ (1G4)
levels has allowed us to identify previously unreported Tm3+ (1G4 -->
H-3(5)) emission.