DISCUSSION 77 



just want to point out that the spin of the (juencher plays no role if the 

 quenching process takes place by charge transfer from the triplet to the 

 quencher or vice versa, because then the charge will be transferred in the 

 complex with the same spin. 



Dr. Portkr: If that is the mechanism. 



Dr. I.in.schu/.: But that is. in fact, the mechanism. 



Dr. Porter: You would then expect a correlation witii redox potential or 

 something like that, which you don't get. 



Dr. Linschitz: But you do. 



Dr. Porter: I don't. .And you would expect diamagnetics to quench as 

 well. 



Dr. Linschitz: Which you do find. 



Dr. Porter: Which ones? 



Dr. Linschitz: Quinones and hydroquinones. 



Dr. Porter: Ah, but other mechanisms become possible there. 



Dr. Seliger: Why, in the case of phenanthrene-naphthalene triplet-triplet 

 quenching could it not be explained by a resonant energy transfer from the 

 excited phenanthrene singlet to the naphthalene singlet and then to the 

 naphthalene triplet? 



Dr. Porter: You need an energy considerably greater than kt to go from 

 the phenanthrene singlet to the naphthalene singlet. You just haven't got 

 enough energy to make the transition and the system was chosen for that 

 reason. This is an unequivocal case. There are others that we studied which 

 were not unequivocal in this sense. 



