scholarly journals X-ray Version of Davisson-Germer Experiment

Author(s):  
Bhanumoorthy Pullooru

Abstract Application of unitcell defined boundary conditions leads to the question on the formation of standing waves within unitcell. We design and propose X-ray version of Davisson-Germer experiment as the answer. In the proposed experiment, a tunable synchrotron beam replaces the variable de Broglie wavelength of incident electron beam. Among the two series of Davisson-Germer peaks from original experiments available in literature, first series shown in figure 1 demonstrates standing wave description and the second series shown in figure 2 demonstrates running wave description. Both running waves and standing waves cannot simultaneously exist within the unitcell and the proposed experiment alone can resolve between the two. The experiment can be conducted on a macromolecular crystal also.

Author(s):  
A.E. Curzon

The heating effect of an incident electron beam may cause a material to be radiation-sensitive. For example, the adsorption behaviour of inert gases on graphite observed in a transmission electron microscope depends critically on the temperature of the substrate. Early consideration of beam heating dealt with a circular film illuminated at the centre by an electron beam of circular cross-section. In practice, however, the film is often supported across a square aperture and is not centrally illuminated. It has recently been shown that the method of images may be used to solve the problem of the heating of a square film of thermal conductivity k by a beam whose cross-section is entirely within the film. This solution has the advantage that it applies regardless of where the incident electron beam strikes the film. The general solution involves an infinite sum over a two dimensional lattice of heat sources and sinks. Though the sum is readily evaluated by means of a computer, it is helpful to consider a particular limiting case which is readily understood in terms of three images and the main beam. This case is illustrated in Figure 1.


The concept of “Standing Waves” (SW) that arise in the crystal dynamically “attacked” by the frequency fields X is analytically analyzed towards expressing, in almost all the cases, the total intensity of the fields on dispersion branches in the perfect crystal and for the embedded layer on the imperfect crystal using various extensions of the semi-classical dynamic theory, adapted or reparameterized, depending on the specific conditions of analysis performed.


Vacuum ◽  
1976 ◽  
Vol 26 (10-11) ◽  
pp. 421
Author(s):  
J.P. Coad ◽  
M. Gettings ◽  
J.C. Rivière

2005 ◽  
Vol 76 ◽  
pp. S152
Author(s):  
B. De Smedt ◽  
N. Reynaert ◽  
F. Flachet ◽  
M. Coghe ◽  
L. Paelinck ◽  
...  

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