I want determine the fluorescence quantum yield for my samples and in this measurement I used tris(2 2′-bipyridyl)dichloro ruthenium(ii) hexahydrate as a standard material.
Please see at the attached file for more inform.
After Calculating I got the QE values is too small and as I know have a big difference QE value whether or not presence of Oxygen.
Could you show me more clearly? and how can I get the QE value in absence? any calculating can transmit them?
Thank you so much!
Typically, when it comes to transition (both d- and f-) metal complexes, population of the emitting state often goes through a triplet state, either ligand triplet state, or 3MLCT (metal-to-ligand charge transfer). These triplet states are quenched by oxygen, therefore the quantum yield goes down.
By the way this is one mean of proving that a triplet state is implied in the energy transfer.
In order to remove oxygen (I suppose you work with solution samples), you have to degass the solutions. One way is to go through freeze-thaw cycles under vacuum. Another one is simply to gently bubble argon or nitrogen (cheaper!) into the solution and then keep the inert gas atmosphere above the solution. In the latter case, be careful not evaporating the solvent or, better, remeasure the absorption spectrum after the operation.
You may wish to read the attach article.
Typically, when it comes to transition (both d- and f-) metal complexes, population of the emitting state often goes through a triplet state, either ligand triplet state, or 3MLCT (metal-to-ligand charge transfer). These triplet states are quenched by oxygen, therefore the quantum yield goes down.
By the way this is one mean of proving that a triplet state is implied in the energy transfer.
In order to remove oxygen (I suppose you work with solution samples), you have to degass the solutions. One way is to go through freeze-thaw cycles under vacuum. Another one is simply to gently bubble argon or nitrogen (cheaper!) into the solution and then keep the inert gas atmosphere above the solution. In the latter case, be careful not evaporating the solvent or, better, remeasure the absorption spectrum after the operation.
You may wish to read the attach article.
Prof. Bunzli is absolutely right, the excited states of ligands are quenched by oxygen. However, recently i found that the luminescence of some inorganic salts of cerium(III) in water, are also quenched by molecular oxygen. Have you meet with similar effects?
Thank you in advance!
@Dim. Long time ago I met a similar effect with Tb(III) in presence of nitrate. In your case, Ce(III) is likely oxidized into Ce(IV) since this species is in equilibrium with Ce(III) in water.
indeed, the "chemical quenching" is possible. Thanks so much for the answer.
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