Excited‐state electronic Raman scattering of alexandrite

Raman scattering is used to investigate the electronic excited‐states of alexandrite at low temperature (13 K). The Raman spectra of Cr 3+ ions in two non‐equivalent types of crystal field sites, one having mirror symmetry C s the other having inversion symmetry C 1 , are reported. With λ e = 514.5 nm excitation, the Raman transitions of the metastable state 2 A ′ (R m1 ) → 2 A ″(R m2 ) and 2 A ′(R m1 ) → 2 A ″( 2 T 1 ) of Cr 3+ in the C s site are 36 cm −1 and 600 cm −1 , respectively; with λ e = 488.0 nm excitation, the Raman transition between 2 A g (R 11 ) and 2 A g (R 12 ) of Cr 3+ in the C 1 site is 116 cm −1 .