Question

The relationship between spread out film (S) and the radius of the powder camera (R) in Debye-Scherrer powder diffraction is (where \(\theta\) is the angle):

• A. \( R = 4S\theta \)
• B. \( S = 4R\theta \)
• C. \( R = S\theta \)
• D. \( S = R\theta \)

Hint:

Remember, in Debye-Scherrer diffraction, the arc length on the film is directly proportional to both the radius of the camera and the scattering angle, with a factor of 4 due to geometry.

Answer 1

The Correct Option is B

In Debye-Scherrer powder diffraction, a monochromatic X-ray beam is used to analyze powdered crystalline samples. The X-rays are diffracted by the crystal planes and the resulting pattern is captured on a photographic film that wraps around the sample inside the camera.
The Debye rings form on the film due to constructive interference, and the relationship between the arc length on the film (S), the camera radius (R), and the scattering angle (\(\theta\)) is given by:
\[ S = 4R\theta \] Here, \(\theta\) is the angle between the incident beam and the diffracted beam. The factor 4 appears because the arc subtended on the film by the diffracted rays involves a geometric projection based on the camera’s curvature and detection method.