The zero-phonon line and the structured multiphonon sideband of the R2 absorption in KF have been investigated in the temperature range 2-100 K. The values of the Huang-Rhys factor (approximately 2) and of the Debye temperature (241 K) were determined for R2 transition. Transverse acoustical phonons propagating along <100> directions are most likely involved in the coupling of the F3 centres with the KF host lattice.
Coluzzi, R., Scacco, A., Somma, F., Baldacchini, G., Ciaramella, E., Montereali, R.m., et al. (1991). ZERO-PHONON LINES IN THE R2 ABSORPTION OF F3 CENTERS IN KF. SOLID STATE COMMUNICATIONS, 79(3), 201-204 [10.1016/0038-1098(91)90634-8].