102 



BURTON: This is interesting. It ought to be possible to produce a mech- 

 anism of protection, shouldn't it? If one can provide for a resonance transition 

 from a molecule that you want to protect to some other molecule containing an 

 ethylenic linkage, then it should be possible to go down all the way to the lowest 

 state without any decomposition. That would be a new case of sponge- type pro- 

 tection. 



What you do is to introduce a molecule there in which there is a high proba- 

 bility of the type of resonance transition that Dr. Linschitz was discussing be- 

 fore, a high probability of such a resonance transition to a molecule in which 

 there is an ethylenic linkage. Then the latter molecule, excited in this way, 

 degrades very rapidly to the ground state without resultant chemical effect. 



POLLARD: It does not work biologically. 



BURTON: It has been tried? 



POLLARD: Anything you do with a good biological protein stops its function. 



KASHA: There is one place where Dr. Burton's suggestion has been ex- 

 ploited in a practical way. Plastics decompose with light. There is a photo- 

 stabilizer -- this is just sort of backward --in which the triplet state is pro- 

 duced with the probability of unity and what seems to happen is that the light 

 is absorbed largely by the big chain molecule; that is, energy gets into this 

 stabilizer which then goes to its triplets and just gives out its heat, and so it 

 does remove the energy which normally cause the breakdown of the plastic. 



KAMEN: What is the reference on that? 



KASHA: Burgess (23). 



PLATZMAN: Does the lowest excited state ever go to the ground state? 



KASHA: I think it is very rare and, incidentally, internal conversion to the 

 ground state I think is fairly rare in most molecules which are not ethylenic but 

 occasionally it may happen. If it is a quantitative matter only, as I tried to in- 

 dicate, then if the lowest singlet state is close to the ground state, it may ac- 

 tually degrade. 



PLATZMAN: In my opinion, one must be more than a little wary about 

 identifying chemical availability and chemical effectiveness of energy with the 

 existence of a low triplet state. 



KASHA: If the triplet state is an emitting state then that would be available 

 energy, I would say. In other words, in this suggestion of Dr. Magee's about 

 water, I think the most interesting thing to do is to see whether you can get lum- 

 inescence of ice due to that triplet state. 



