V18

Reflectometer for biological applications (BioRef)

BioRef is a time-of-flight reflectometer which is intended to focus on soft matter applications, especially at solid–liquid interfaces, for the investigation of biological model systems under physiological conditions including kinetic studies. The instrument was built in a joint collaboration between HZB and the University of Heidelberg with financial support by the BMBF Verbundforschung. Unique features of BioRef are the chopper system, which allows for focusing on a certain Q-range in order to support fast kinetic studies, and the availability of optional in situ IR spectroscopy measurements that provide conformational information under the same experimental conditions under which simultaneously the neutron reflectivity is providing structural data.

A special feature of the instrument is an add-on sample environment that allows for simultaneous in situ infrared (IR) spectroscopy of the investigated Si-supported interfaces in ATR (attenuated total reflection) geometry. A Bruker Vertex 70 infrared spectrometer is installed above the sample position for the very reason. The IR beam enters the Si substrate through the inclined top surface (45°) under 90°, is then totally reflected internally several times at the sample surface (front side) and the backside of the substrate before leaving the Si-substrate through its inclined bottom face to be deflected into the external IR-detector. The setup enables combined in situ (kinetic) neutron reflectivity and IR studies with depth profile and conformational information acquired at the same time.