B. Villacampa et al., PHONON STRUCTURE OF CR3-DOPED MAF(3) (M=CD, CA A=RB, CS) CRYSTALS( PHOTOLUMINESCENCE IN CHROMIUM), Journal of luminescence, 63(5-6), 1995, pp. 289-296
The structure of the luminescence band of Cr3+ ions in CsCaF3, CsCdF3,
RbCaF3 and RbCdF3 has been measured and analyzed using decay time mea
surements and time-resolved spectroscopy. The observed emission corres
ponds, in cubic Cr3+ centers, to the transition from the lowest spin-o
rbit (SO) component of the T-4(2g)(F-4) level to the (4)A(2g)(F-4) gro
und state. The structure has been associated with the zero phonon line
s (ZPL) and vibrational replicas of several types of Cr3+ centers, mai
nly cubic and trigonal ones. Four different phonon modes have been fou
nd in each of the crystals. Their frequencies change with the host cry
stal but not with Cr3+ symmetry. A tentative assignment of these phono
n frequencies to normal modes of the [CrF6](3-) complex has been propo
sed and discussed. The Cs compounds show a satellite at 14 cm(-1) in t
he high energy side of each of the lines. It has been associated with
the emission from the next SO component of the T-4(2g) level. The stro
ng reduction of the SO coupling constant with respect to the free ion
value is likely due to a dynamic Jahn-Teller effect.