Quenching through energy transfer

Figure 15. Fluorescence spectrum of the [Zn (cyAn)P complex. Low intensity profiles refer to cyAn itself (quenching through electron transfer from the proximate tertiary amine nitrogen atom) [Ni (cyAn)P and [Cu (cyAn)P complexes (quenching through energy transfer to metal centred low energy levels).

Furthermore, upon encapsulation and formation of dendrimer-encapsulated dyes, new fluorescence properties which were different from each constituent were observed and assigned to quenching/sensitization processes. The fluorescence of peripheral dansyl groups of the dendrimer was totally quenched through energy transfer by the encapsulated dyes while hosted dyes experienced partial quenching. 

Figure 8.21 gives a schematic representation of the type of photophysical experiments which can be performed in L-B films. The distance dependence of a quenching action through energy transfer or electron transfer can be... 

Fig. 20 Energy level scheme and electronic transitions in 35. Upon excitation (ex) of HBC, either singlet energy transfer (EET) to the PMI periphery or intersystem crossing (ISC) to the HBC triplet state (Tj) occurs. In the case of EET, PMI fluorescence ( / ) is observed while population of Ti leads to a dark state. After ISC, singlet-triplet annihilation (STA) may quench excited singlet states (Si) of the PMI periphery through energy transfer to Ti. Subsequently, in this example, the higher excited triplet state (r ) decays non-radiatively...

Naturally occurring clay mina-als contain impurities such as Fe that quench the excited state of adsorbed dye species through energy transfer mechanisms. 

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