Stoe Stadivari
What is it?
Single crystal X-ray diffractometry is a technique used to determine the crystalline structure of a material.
How does it work?
A crystal is exposed to an intense beam of X-rays, usually of a single wavelength (monochromatic X-rays), producing a regular pattern of reflections. The angles and intensities of diffracted X-rays are measured by a detector. As the crystal is gradually rotated, previous reflections disappear and new ones appear. The angles at which the crystal diffracts the beam into the detector correspond to planes of the crystals. Each crystal has a characteristic pattern of diffraction angles and corresponding intensity of the diffracted beam.
To identify and characterize the crystal, the interplanar spacing (d-spacing) of a crystal is used. In this case, the wavelength of the incident X-ray is known and measurement is made of the incident angle (Θ) at which constructive interference occurs. Solving Bragg’s Equation gives the d-spacing between the crystal lattice planes of atoms that produce the constructive interference. A given unknown crystal is expected to have many rational planes of atoms in its structure; therefore, the collection of “reflections” of all the planes can be used to uniquely identify an unknown crystal.
What can be measured?
The crystal needs to be at least 0.1 mm in each direction. It should also be pure and absent of structural defects such as twinning.
Sponsor:
Responsibles:
For organic, coordination polymers and hybrid materials:
For inorganic materials and intermetallics: