Measurement of the Intensity - wavelength distribution for monochromatic X-rays

For a given crystal for example sodium chloride (common salt, NaCl) the interatomic distance i.e. the spacing of the planes of atoms (d spacing) is fixed and can act as a three dimensional diffraction grating for sufficiently small wavelength ( ~1Å ) electromagnetic radiation ( in the x-ray region of the spectrum ). The original experiment was suggested by Max von Laue, after a question posed by Ewald, to test whether x-rays were waves and carried out by Friedrich and Knipping in 1912.

The intensity of an x-ray beam diffracted from a crystal can be measured as the count rate detected by a Geiger- Müller tube and the wavelength as the angle of diffraction since from the Bragg equation l µ q for a constant d, see diagram below.

Fill in the table:

Intensity (counts per second)

wavelength (q)