Equipement

Our current X-ray diffraction instrument consists of a Rigaku generator RU200 and a MAR345 image plate detector. The rotating anode can be switched between copper (Cu) and Molybdenum (Mo) radiation.

The anode of choice for small molecule X-ray diffraction experiments (unit cell parameters up to 60Å) is Molybdenum since the shorter wavelength allows data collection to the highest resolution (∼0.8Å) in one image. Moreover the Mo radiation is often less absorbed by the crystal, which allows measuring of heavy atom compositions.

Copper radiation gives more intense radiations in combination with a larger peak separation and is therefore more appropriate for larger samples such as proteins and polynucleotides. As the detector is fixed to the 0° 2theta position (the direct beam hits the center of the detector) the resolution in the Cu mode is limited to about 1.5Å, which is more than sufficient for most biological crystals.

Focusing mirrors are installed for the Cu radiation and a oxford cryostream system allows the sample to be measured in a 80 - 400 K range.

The setup allows experiments on single crystals as well as on powder samples mounted in capillaries.