Excited state decay of tetrahalomanganese(ii) complexes |
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Authors: | Mark Wrighton David Ginley |
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Institution: | Department of Chemistry, Massachusetts Institute of Technology Cambridge, Massachusetts 02139, USA |
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Abstract: | The excitation and emission spectra and decay times of several MnX2-4 (X = Cl?, Br?, 1?) complexes of various tetraalkylammonium, -phosphonium, and -arsonium salts have been measured for the pure solids at 298°K and 77°K. High luminescence quantum yields (0.3-1.0) reveal that lifetimes fairly accurately reflect radiative decay rates. An impressive correlation exists between the lifetime, τ, of the 4T1 (G) →6 A1 emission and the ligand, X: for X = Cl?, τ = 1.2 - 3,5 x 10?3 sec; X = Br?, τ = 0.35 - 0.43 X 10?3 sec; X =l?, τ = 0.036 – 0.055 X 10?3 sec. We attribute this decreasing lifetime largely to the enhanced spin-orbital coupling associated with the heavier halide. We find that direct population of high energy charge-transfer (CT) states gives smaller emission yields than excitations in the ligand-field (LF) region. |
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