Determination of the lattice constants of a monocrystal

Principle

Polychromatic X-rays impinge on a monocrystal under various glancing angles. The rays are reflected by the lattice planes of the monocrystal. An energy detector is only used to measure those radiation parts that interfere constructively. The lattice constant of the crystal is determined with the aid of the various orders of diffraction and the energy of the reflected rays.

Tasks

1. Energy determination of the X-rays that are reflected at the lattice planes of the LiF-crystal for various glancing angles or diffraction orders.
2. Calculation of the lattice constant of the LiF-crystal based on the glancing ngles and associated energy values.

Learning objectives

• Bremsstrahlung
• Characteristic X-radiation
• Energy levels
• Crystal structures
• Bravais lattice
• Reciprocal lattices
• Miller indices
• Bragg scattering
• Interference
• Semiconductor detectors
• Multichannel analysers