Question

When an x-ray beam is scattered off the planes of a crystal, the scattered beam creates an interference pattern. This phenomenon is called Bragg scattering. For an observer to measure an interference maximum, two conditions have to be satisfied:

The angle of incidence has to be equal to the angle of reflection.
The difference in the beam's path from a source to an observer for neighboring planes has to be equal to an integer multiple of the wavelength; that is,
2dsin(θ)=mλfor m=1,2,…2dsin⁡(θ)=mλfor m=1,2,….

The path difference 2dsin(θ)2dsin⁡(θ) can be determined from the diagram (Figure 1). The second condition is known as the Bragg condition

Answer 1

The Bragg scattering phenomenon occurs when an x-ray beam interacts with the planes of a crystal, resulting in the creation of an interference pattern. In order for an observer to measure an interference maximum, two conditions must be met.

The first condition is that the angle of incidence of the x-ray beam must be equal to the angle of reflection. This ensures that the scattered beam is directed towards the observer.

The second condition, known as the Bragg condition, states that the difference in the path length traveled by the x-ray beam from the source to the observer for neighboring crystal planes must be equal to an integer multiple of the wavelength (mλ). This path difference is given by 2dsin(θ), where d is the spacing between the crystal planes and θ is the angle between the incident beam and the crystal planes.

By satisfying these two conditions, the scattered x-ray beam undergoes constructive interference, resulting in an observable interference maximum in the form of a diffraction pattern.