Excitation, electronic experimental evidence, sources

Experimental evidence on excitation transfer derives from different sources. In strongly and weakly coupled systems most of the information has been obtained from absorption spectra and is, thus, rather on the delocalization of excitation. In weakly coupled systems the direct observation of actual excitation transfer is the only source. Depending on the nature of excited states involved, different effects are to be used here, such as fluorescence, phosphorescence, electron-spin resonance and even chemical reactivity. 

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