Physics and Engineering of Radiation Detection

12.1. Spectroscopy of Photons 691

X−ray Source

Output

2θ

Detector

Sample

Photon

Figure 12.1.18: A simple setup for x-ray diffraction spec-

troscopy. The diffracted x-rays make an angle of 2θwith re-

spect to the direction of motion of incident x-rays (see also

Fig.12.1.17).

A typical distribution of photon intensity with respect to the angle of reflection
θis shown in Fig.12.1.19. Each of the peaks shown in the figure corresponds to con-
structive interference of diffracted x-rays. Since these peaks satisfy Bragg’s criteria,
therefore the angle information can be used to determine the atomic plane spacing
through equation 12.1.14.

20 25 30 35 40 45 50 55 60 65

Intensity

2θ(degrees)

Figure 12.1.19: XDS pattern of

WO 3 powder obtained after heat-

ing in air for 8 hours at 90^0 C(re-

drawn from (19)).