XAS, XMCD, XLD Bessy chamber

If the chamber is not on tour at the synchrotron, you find it in room MD 442. It has been designed for X-ray absorption measurements at synchrotron radiation sources.

This portable UHV chamber is designed for measurements of X-ray absorption (XAS) at synchrotron sources, especially BESSY in Berlin. As a key component, the chamber contains a water-cooled coil system. With its help X-ray magnetic circular dichroism (XMCD) can be measured in a static applied magnetic field (up to 50 mT at present).

Prior to beamtimes at the synchrotron, we establish sample preparation and characterization via standard methods of surface science physics in our lab. Thus, we are able to produce samples in situ at the beamline following standard recipes. For sample characterization, the chamber provides Auger electron spectroscopy (AES) and electron diffraction (LEED, MEED). As a special feature, the LEED is equipped with a multi-channel plate detector system which allows for operation with target currents of a few microamps. Thin films can be deposited from electron beam evaporators (single and triple). Organic molecules are evaporated from a Knudsen cell.

Additional equipment:

• l-He continuous flow cryostat for measurements between approx. 40 K and room temperature
• manipulator to move the sample in all three spatial directions and rotate it about its polar angle
• sample heating by electron bombardment for a sample temperature up to 1000 K (e.g. to prepare substrates)
• sputter gun for substrate cleaning
• quadrupole mass analyzer for residual gas analysis
• Recently, the chamber has been upgraded with a sample transfer system.