ELECTRON MICROSCOPY 



luu. 6 



Figure 6 shows another characteristic shape 

 (brick-shaped) of particles found in this sample. 

 (About 15,000 X.) 



Fig. 7 

 In Figure 7 are shown particles that are ob- 

 served occasionally. This particle is surrounded by 

 a halo indicating moisture was associated with this 

 particular particle. The particle is an aggregate 

 of different sized particles standing one on an- 

 other. The variation in width of the particle is 

 manifested by the difference in width of the 

 shadow. The widest portion of this particle is 

 about 0.4 n and its height is about 1.75 y.. (About 

 15,000X.) 



cles. Aggregate particles of Pu-^^O-) rarely 

 consist of more than 5 or 6 cubes. 



The particles shown in Figures 3, 4, 5, 6, 

 and 7 were collected directly on tungsten ox- 

 ide and carbon preshadowed specimen 

 screens. The specimens were shadowed again 

 with chromium at a 30° angle before exam- 

 ination in the electron microscope. Double- 

 shadowed particles therefore would indicate 

 contaminants on the specimen grid prior to 

 exposure to the aerosol. 



Physical Data. Pertinent information on 

 the physical characteristics of the particles 

 from each of the aerosols is presented in 

 Table 1 and Figure 8. 



The data and observations presented 

 above are very general in that they were 

 based on measurements of 100 particles rep- 

 resenting a single aerosol. However, analysis 

 of other aerosols containing Sr^''S04 , Ru^"®- 

 O2 , or Pu-^^02 gave similar results. Al- 



Table 1. Physical Characteristics of 



Particles from Aerosols Containing 



Sr^oSO* , RU106O2 , OR Pu^^Oa 



76 



