35 



time 10" 11 second. It may be greater; I have been trying to calculate this 

 time by applying the theory suggested by Landau for the polarization of a crystal 

 which turned out to be wrong for the crystal case but, I think, might apply here. 

 I don't have any results to report on this, as yet. It does not concern the main 

 picture because we are certain that the time cannot be shorter. The energy of 

 the hydrated electrons, that is, the total energy of solution, by analogy to the 

 case of ammonia, turns out to be about 2 electron volts, and the mobility of the 

 "trapped" electron turns out to correspond to an effective electron mass of about 

 l/5 of an ionic mass. 



The second important "delay" is that required for the hydrated electron to 

 dissociate into H + OH". It is amusing to note that this process bears close 

 analogy to orbital capture of an electron by a nucleus. There, too, the elec- 

 tron collapses and produces a permanent change. I have not yet been able to 

 calculate the time required by this process; a preliminary and rough estimate 

 gave 10*9 second. On this time hinges the possibility of observability of the 

 transient hydrated state of the secondary electrons. If they should be fairly 

 stable in the hydrated state, they might conceivably be observable. If the time 

 is very short they probably never can be, except indirectly through their in- 

 fluence on the chemical kinetics. 



BURTON: In terms of your own restriction I think the statement must be 

 modified. You said this is physically pure water. After all, there are compet- 

 ing processes in real water. 



PLATZMAN: All of them would tend to shorten the total time. 



To get an idea as to the observability by optical means, suppose that we 

 took a column of pure tritium water about 10 centimeters long and looked for 

 the blue color. What would the lifetime for attachment have to be in order to 

 observe it? It turns out that it would have to be at least 10 _ 5 second, which is 

 highly unlikely. 



LINSCHITZ: I don't quite see the mechanism by which you use the solvation 

 energy of the electron to help process (A) go. How do you couple the solvation 

 energy around the electron to any other process that would help you hydrate the 

 OH? 



PLATZMAN: The water molecule to which attachment takes place is sup- 

 posed to be inside the "orbit" of the electron. 



LINSCHITZ: It has to be inside the same hole. 



PLATZMAN: There are several water molecules inside the orbit. Attach- 

 ment to one outside would not take place. 



LINSCHITZ: This electron is by itself and if you use it essentially to make 

 a hole in the solvent 



PLATZMAN: There is no actual hole there. I don't like that word. It is 

 often confused with the "potential well". 



ALLEN: There is a real vacancy there. When these things orient they 

 expand somewhat. 



PLATZMAN: They push apart. That is correct. The density becomes 

 smaller. This is known not only in the figure that Professor Onsager cited; it 

 is also known from the crystal, when electrons are trapped. But this does not 



