Raman scattering of chromium-doped halide elpasolite crystals

Review—Photoluminescence Properties of Cr3+-Activated Fluoride Phosphors

“…3-(CrF 6 ) molecules observed in the various Cr 3+ -doped fluoride phosphors. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The IR-active (ν 3 and ν 4 ) and silent vibration frequencies (ν 6 ) can in principle be obtained from measuring PL spectra, whereas the Raman-active ν 1 , ν 2 , and ν 5 frequencies are determined from Raman scattering measurements. 25,26 In the Mn 4+ -activated hexaflorometallate phosphors like A 2 MF 6 :Mn 4+ and BMF 6 :Mn 4+ (A = alkaline metal element or NH 4 molecule; B = alkaline earth metal element; M = group-IV metal element), the vibration frequencies of the metal complex MF 6…”

Raman and magnetic susceptibility studies of hexagonal elpasolite Cs2NaAlF6:Cr3+

“…It is worth noting that the positions of the vibrational bands in several elpasolites systems are similar [17][18][19][20][21][22]. Of the sixteen Raman-active modes, only five (two A 1g and three E g ) are normally observed between 200 and 600 cm -1 .…”

Two-photon excitation spectroscopy of Cr3+:K2NaScF6elpasolite: II. Theoretical models

“…It softens at low temperature, precipitating a phase transition that presumably stabilizes its frequency and may enable it to become Raman active. The room-temperature Raman line corresponding to the lowfrequency t 2g mode at 113 cm −1 splits into several components in the low-temperature (90 K) Raman spectrum [22], with frequencies ranging from 93 cm −1 to 135 cm −1 , while a new line appears at 45 cm −1 . The low-temperature emission spectrum (2.1 K) (I) reveals a prominent line at 63 cm −1 with a shoulder at 121 cm −1 that cannot be resolved further.…”

“…The t 1g mode is not Raman active in the high-temperature phase [22]. It softens at low temperature, precipitating a phase transition that presumably stabilizes its frequency and may enable it to become Raman active.…”

“…The vibration frequencies associated with extended progressions, 106 cm −1 and 310 cm −1 , must be identified with low-dispersion, zonecentre optical modes in order to explain their persistent resolution. Lattice-mode frequencies measured by Raman scattering [22] and calculated from a lattice-dynamics model [23] are presented in table 1. Local-or resonance-mode frequencies derived from emission spectra in I, also listed in table 1 for comparison, differ little from those of corresponding lattice modes.…”