Raman scattering in silicate garnets: an investigation of their resonance intensities

✍ Scribed by B. A. Kolesov; C. A. Geiger

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 327 KB
• Volume: 28
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199709)28:9<659::aid-jrs156>3.0.co;2-7

✦ Synopsis

The intensity of Raman modes of four di †erent silicate garnets in the energy range 1.9-2.7 eV was investigated. In the case of almandine and pyrope no change in intensities was observed in this (Fe 3 Al 2 Si 3 O 12 ) (Mg 3 Al 2 Si 3 O 12 ) energy region and in uvarovite a weak resonance maximum was observed between 2.2 and 2.4 eV. (Ca 3 Cr 2 Si 3 O 12 ) Andradite however, showed a strong resonance in the blue energy range with two maxima at 2.4 (Ca 3 Fe 2 Si 3 O 12 ), and 2.6 eV. The strongly enhanced resonances in andradite, compared with the other three garnets, is thought to be caused by electronic transitions in the states of Fe3' in the octahedral site. The individual resonance behavior of e g two components and of the same twofold degenerate mode related to the tetrahedron can be (E g ,1 E g ,2) E g SiO 4 distinguished by the interaction of the respective Raman and Fe3' electronic tensors. 1997