Polarized electronic absorption spectra of 3d3-configurated tetravalent manganese in octahedral fields of Mn(SeO3)2 |
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| Authors: | M Wildner K Langer |
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| Institution: | 1. Institut für Mineralogie und Kristallographie, Technische Universit?t Berlin, Ernst-Reuter-Platz 1, D-10587, Berlin, Germany
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| Abstract: | Polarized optical absorption spectra of Mn(IV) in octahedral crystal fields of Mn(SeO3)2 have been studied by means of microscope-spectrometry in the range 40000-4000 cm?1 and at temperatures between 113 K and 293 K. Intense charge-transfer absorptions (linear absorption coefficient α ? 30000 cm?1) completely mask the d-d transitions in the UV and VIS region above ≈23000 cm?1. The optical electronegativity χ opt of Mn(IV) in Mn(SeO3)2 is estimated to be 2.7. In accordance with the d 3 configuration of tetravalent manganese three d-d bands observed at ambient temperatures at 13250, 14137 (α≈50 cm?1) and ≈18500 cm?1 (α≈500–800 cm?1) are assigned to the spin forbidden 4 A 2g →2 E g and 4 A 2g →2 T 1g transitions as well as to the first spin allowed 4 A 2g →4 T 2g transition, respectively. These assignments allow the calculation of the following ligand field parameters: Dq ≈ 1850 cm?1, B 55 = 869 cm?1 (β 55 = 0.82), and C = 2346 cm?1 (293 K). |
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