XV. ELECTRONS, NEUTRONS, AND ALPHA PARTICLES 



517 



crease with increasing ion density as observed in the case of tyrosine 

 and carboxypeptidase. 



It is, howevei', only legitimate to consider both types of radical 

 randomly distributed throughout the column as long as the distance 

 between successive OH radicals (always formed near the axis of the 

 column) is comparable with the column radius. Figure 9 shows that 

 while this is true for fast electrons it is of doubtful validity for a 1 

 kv. electron and is certainly not the case for a. radiation. Lea has 



TRACKS OF IONIZING PARTICLES 



a PARTICLE 



I kv. ELECTRON 



= 8 X lO"* p. 



a/a = I 06 in 10"" sea 



6=^1.5 X 10"^^ 



i)'/6 = l02 m 10"' sec 



60 kv ELECTRON 

 o'/o = b'/b -- 7.6 in 2 x 10"* sec 







® 



® 



= 6= I 5 X 10"^ M 



® 



[h] = [OH] = I 3 X 10"* M 



b a 



e ®Q 00 [oh] = 4xio"''m 



b a 



© © 



© © ® [h] = [0H]=7xI0"'M 



© ® © 



b--a 



Fig. 9. Diagram showing spatial distribution of hydroxy! radicals and hydro- 

 gen atoms, derived, respectively, from positive and negative ions, at the moment 

 of formation by a 60 kv. electron, a 1 kv. electron, and an a particle. Broken 

 lines show expansion of columns during time that 50% of the radicals make one 

 collision, a and a' are the radii of the positive ion column before and after 

 diffusion; b and b' are radii of negative ion (•(jjuinii befoie and after diffusion. 



computed the manner in which the concentration of each type of radi- 

 cal varies \Aith distance from the axis of an a-ray track at different 

 times after the moment of formation (see Fig. 10). Noting that con- 

 centrations are plotted on a logarithmic scale it will be seen that for 

 a considerable period of time the hydroxyl concentration in the innei- 

 column greatly exceeds that of the hydrogen atoms. During this 

 time OH radicals will ha^'e made a large number of mutual collisions. 



