APPLICATION OF ELECTRON DIFFRACTION 



595 



{331} REFLECTION 



CRYSTAL SURFACE CONTAMINATED BY ADSORBED GAS 



Fig. 3- 



{331} REFLECTION 



CRYSTAL SURFACE CLEAN 



-Development curves of a (331) reflection before the removal of surface gas, 

 and after 



{551} REFLECTION 



CRYSTAL SURFACE C0NTAK/1INATED BY ADSORBED GAS 



{551} REFLECTION 



CRYSTAL SURFACE CLEAN 



Fig. 4 — Development curves of a (551) reflection before and after the removal of 



surface gas 



