ELECTRON TRANSMISSION THROUGH THIN METAL SECTIONS 



871 



□ 1ST ZONE 

 ^ 2ND ZONE 

 S3RD ZONE 



BRILLOUIN 

 /ZONE 

 / BOUNDARY 



AK 

 VACUUM I CRYSTAL I VACUUM 



(b) 



Fig. 3 — (a). First three Brillouin zones for a simple square lattice. In an actual case, 

 I K\ 

 \g\ is of the order of 0.5yl~^ and — about 19A~^. 



\2ir\ 



(b). Relation among wave vectors in reciprocal space for the kinematic and for the 

 dynamical theories. The wave vectors must satisfy the Bragg condition and the boundary 

 conditions at the crystal faces. The dynamical theory introduces the beat wave vector 

 AK. Kv is the vacuum incident wave vector. 



h- 



\Vg[ 



m 



sin^ ^AKz 



+ \Vg\' 



(1) 



where Vg = Fourier coefficient of potential 



Ag = deviation from the Laue condition in volts 



