226 



Subsurface Geologic Methods 



screens broaden the pattern lines and thereby decrease definition. Patterns 

 so produced have little value for determining the constitution of complex 

 mixtures, for maximum definition with minimum line width is desired to 

 permit measurement of the maximum number of lines. 



X-Radiation 

 The use of the Ka doublet radiation from molybdenum has been rec- 

 ommended for chemical analysis by the X-ray-diffraction or Hanawalt 

 method.^"* This radiation might be suitable for the identification of pure 



Back reflection 

 film 



Cylindricol film-' ^-Flof film 



Figure 96. Film positions in various cameras used for powder studies. 



TABLE 8 



Angular Range of Corresponding Patterns Produced by Common Target 

 Materials Compared to Pattern Range of Chromium Ka Radiation 



^* Tentative Recommended Practice for Identification, of Crystalline Materials by the Hanawalt X-ray 

 Diffraction Method: Am. Soc. Testing Materials designation E43-42T, 1942. 



