Malíčková I., Bačík P., Fridrichová J., Hanus R., Štubňa J., Milovská S. & Škoda R., 2020: Detailed luminescence spectra interpretation of selected oxides: spinel from Myanmar and chrysoberyl – var. alexandrite from Tanzania. Acta Geologica Slovaca, 12, 1, 69–74.

Detailed luminescence spectra interpretation of selected oxides: spinel from Myanmar and chrysoberyl – var. alexandrite from Tanzania

Iveta Malíčková¹, Peter Bačík^1,2, Jana Fridrichová¹, Radek Hanus³, Ján Štubňa⁴, Stanislava Milovská⁵ & Radek Škoda⁶

¹Comenius University, Faculty of Natural Sciences, Department of Mineralogy and Petrology, Ilkovičova 6, 842 15 Bratislava, Slovakia, malickova3@uniba.sk, peter.bacik@uniba.sk, jana.fridrichova@uniba.sk
²Earth Science Institute of the Slovak Academy of Science, Dúbravska cesta 9, 840 05, Bratislava, Slovakia
³Gemological Laboratory of e–gems.cz, 110 00 Prague, Czech Republic; kakt@centrum.cz
⁴Gemmological Institute, Faculty of Natural Sciences, Constantine the Philosopher University in Nitra, Nábrežie mládeže 91, 949 74 Nitra, Slovakia; jstubna@ukf.sk
⁵Earth Science Institute of the Slovak Academy of Sciences, Ďumbierska 1, 974 01 Banská Bystrica, Slovakia; milovska@savbb.sk
⁶Masaryk University, Faculty of Science, Department of Geological Sciences, Kotlářská 2, 611 37 Brno, Czech Republic; rskoda@sci.muni.cz

Abstract

Different structure and symmetry of spinel and chrysoberyl influence their luminescence spectra Observed with Raman spectroscopy. Luminescence bands of spinel at 677, 685, 697, 710 a 718 nm were assigned to Cr³⁺. Luminescence duplet located at 685 and 687 nm belongs to R₁ and R₂–lines for the Cr³⁺ ion, the electron transition ²Eg → ⁴A_2g, N₁ and N₄ at 687 and 700 nm; N₃ (689 nm) is weak. Luminescence centers of alexandrite located at 644, 650, 653, 667, 669, 678, 680, 690, 694, 702, 707, and 716 nm were assigned to Cr3+. R–lines assigned to 679 with 677.3 nm, and 694.4 with 691.7 nm, accompanied by N–lines of Cr–Cr pairs. Luminescent duplet of alexandrite at 680 nm is associated with electron transition ²Eg → ⁴A_2g. The R–lines in chrysoberyl are located at 678 nm (R_m–line) a 690 nm (R_i–line). Lower symmetry of the structure and Cr₃₊–bearing octahedra results in splitting, widening and overlapping of the luminescence bands in spectrum. Spinel with higher symmetry than chrysoberyl has the luminescence spectrum with smaller number of better resolved bands.

Key words: luminescence, Raman Spectroscopy, spin–forbidden transition, spinel, alexandrite

Manuskript doručený: 2020-04-30

Manuskript revidovaný: 2020-06-16