13 



POLLARD: I should like to know that, too. 



PLATZMAN: Perhaps that should come before we talk about them as 

 though the difference had been clearly delineated. 



BARRON: I think I will have something to say this afternoon. 



KAMEN: What was that business of no migration in the dry state? 

 How does that fit into this picture? 



POLLARD: No migration? 



KAMEN: In your fact No. 7 you said that there was no migration of 

 radiation energy in the dry state. 



PLATZMAN: It was not "no migration. '' It was limited migration. 



POLLARD: I said it does not readily migrate. I would like to go on 

 with this and to have some discussion. Particularly, I should like Dr. Platzman 

 to comment on this because one of the things that I am highly interested in is the 

 return of the electron to the positive ion. Last year, he gave quite an interesting 

 discussion of electrons below the energy of the first excited state and how they 

 behave. I am inclined to think that is also very crucial in this context, because, 

 if what I have said is right, the events are devastating to any molecule, but 

 something terminates the holding of excitation energy, and it may terminate so 

 fast that possibly this is still not a very important process. In other words, 

 maybe the recombination occurs before these things have time to migrate at all. 

 This should be calculable. 



The feeling I had from your discussion on water was that recombination 

 was not likely to occur very fast, and if recombination does not occur in this 

 case either, then I am quite sure that some sort of mechanism like this of energy 

 migration will be of great importance. 



PLATZMAN: But if I may quote Pollard, from the last conference, 

 the medium here is not water. One should take care in extrapolating the results 

 from one medium to another. 



POLLARD: I believe that I have been going a little fast on one point, 

 and so I would like to illustrate the kind of thing that we can do by showing you 

 a slide of an apple blackening. 



This shows our basic method of working, in a very raw way. It is not 

 something that we have published and I don't want to have it pinned on me that 

 this is how I measure my molecular weights. But I do want to illustrate how 

 you could go about measuring molecular weight with only these data. These data 

 were taken by Mr. Bellamy at General Electric. 



The picture represents pieces of apple that have been exposed to the air 

 for fixed lengths of time. They have been bombarded by ionizing radiation -- 

 mainly, I think, fast electrons. The control sample has become brown as an 

 apple does. The samples that have been irradiated get less and less brown, and 

 finally the one that has had 1,000,000 r is preserved and is as white as the origi- 

 nal apple before its exposure to air. 



I asked Bennett, just before everybody gathered, to look at this and to 

 estimate the percentage of color remaining in the various samples. I have set 



