4. Recording diffraction data

The aim of this step is to find for each crystal used, the mesh parameters, the space group, and to obtain for each possible reflection, characterized by its indices hkl, the intensity of this reflectionI _hkl and its associated error σ (I _hkl ), which then enables us to calculate the modulus of the structure factor |F _hkl | and its associated error σ (|F _hkl |). For simplicity, a diffraction data collection experiment consists of several elements (figure 3 ):

• a device for preparing the crystals for collection (usually loop mounting or tests directly on the...