Optical Investigations of Alkali Metal Thiomanganates(II) Containing Isolated Complexes as Well as Chain and Planar Compounds

Autor:	Hans-Herbert Schmidtke, Ulrike Rosellen
Rok vydání:	2002
Předmět:	Arrhenius equation Absorption spectroscopy Chemistry Doping Analytical chemistry Atmospheric temperature range Alkali metal Inorganic Chemistry symbols.namesake Excited state symbols Physical and Theoretical Chemistry Luminescence Excitation
Zdroj:	Inorganic Chemistry. 41:856-863
ISSN:	1520-510X 0020-1669
DOI:	10.1021/ic010333c
Popis:	Tetracoordinated Mn(II) complexes providing different molecular structures were investigated using various spectroscopical procedures. Na 6 MnS 4 contains separate pseudotetrahedral Mn-S complex units, K 2 MnS 2 has chains of edge-shared tetrahedra, and Cs 2 Mn 3 S 4 crystallizes in corresponding layers. Also doped materials, i.e., Cs 2 (Mn x Zn 1 - x ) 3 S 4 with 0.0 < x < 1.0, are considered. Absorption spectra recorded from samples incorporated in polyethylene pellets and excitation spectra taken from pure materials at 15-20 K temperature are assigned on the basis of energy level calculations obtained from the angular overlap model. All compounds exhibit intensive emission in the red, some of them also in the yellow region, which both are investigated in the temperature range from 12.5 to 250 K, in some cases varying the excitation power and excitation wavelength. Decay measurements supply lifetimes and activation energies evaluated from Arrhenius plots. The results support an assignment of both types of emissions to MnS 4 complex entities for all compounds, the red emission from the lowest excited level (Kasha luminescence) and the yellow emission, observed for some of the compounds with increasing intensity at lower temperature, from higher electronic levels.
Databáze:	OpenAIRE
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