Equipment  

The X-ray Absorption Spectroscopy group, which is part of the SSRL Biotechnology Group has a wide variety of equipment that is available for use by experimenters. Although maintained by the Biotechnology group the XAS equipment is available to all users at SSRL, and in addition to biological experiments the XAS equipment is used by experimenters in the materials and environmental sciences. This page describes some of the equipment that is currently available.

Cryostats

Several Oxford Instruments Liquid helium flow cryostats are available. These operate in the temperature range 4-200K and are most useful in providing access to low temperatures. Most biological XAS experiments at SSRL are conducted at 10K, which provides some protection from photo-reduction and enhancement of the EXAFS by freezing out the vibrational components of the Debye-Waller factor.

X-ray Fluorescence Detectors

The SSRL Biotech XAS group has a number of Canberra multi-element germanium detector arrays, and several Stern-Heald-Lytle detectors. One 30-element Germanium detector is permanently located at beam line 7-3, and another at beam line 9-3. while the other three 13 element detectors are mobile and are available on all XAS compatible beam lines. In cases where the ambulatory 13-element detectors are oversubscribed, they are allocated to experiments according to experimental need and to proposal rating.

Motorized Rails

Several motorized rails systems are available for easy alignment of the flight path of the beam. Beam lines 7-3 and 9-3 have motorized rails permanently installed.

Grazing Incidence XAS

Grazing incidence XAS is useful for studies of surfaces and interfaces. The SSRL Biotechnology group has developed a grazing incidence XAS apparatus which can be installed on all beam lines except for 4-1 (due to space limitations). The apparatus is fully motorized and computer controlled (18 axes) and can measure reflectivity curves and a variety of other useful motions.