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X-Ray Spectroscopy & Imaging

SSRL has five hard X-ray Spectroscopy beamlines and three Microfocus Imaging beamlines dedicated to Biological and Biomedical research funded by the NIH and DOE-BER. The SMB group supports and develops technical instrumentation and theoretical methods for state-of-the-art tender and hard X-ray spectroscopy and EXAFS studies on metalloproteins, cofactors and metals in medicine. The SMB group has also contributed to the development of a wiggler end-station beamline and facilities for X-ray emission and Raman spectroscopy, HERFD and RIXS measurements on biological and biomimetic systems. A holistic methodology combining spectroscopy and X-ray fluorescence has been developed on three beamlines encompassing μm-cm scale specimen over the tender & hard X-ray regime integrating hardware and software for seamless measurement across the stations.

X-ray Absorption Spectroscopy

X-ray absorption spectroscopy (XAS) is a well-established technique for simultaneous local geometric and electronic structure determination of a metalloprotein active site. XAS is element specific and sample state agnostic, making it ideal for dilute biological solutions. SSRL has two hard x-ray and two tender x-ray biological XAS beamlines, together covering 2-30 KeV. The beamlines are equipped with specialized instrumentation, including low temperature (liq He) cryostats, solid-state Ge and Silicon drift detectors for dilute samples.

Beam Lines: 9-3 7-3 4-3 14-3a

Techniques

  • Low-temperature XAS
  • Single-crystal XAS
  • EXAFS

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X-ray Emission Spectroscopy

X-ray emission spectroscopy (XES) is a core-level electronic structure determination experimental technique which gives information on orbital splitting, spin and oxidation states as well as the local symmetry and coordination. Beamline 6-2b is a versatile station, equipped with a custom-built, high-resolution analyzer crystal instrumentation, which allows for the measurement of both resonant and non-resonant XES on dilute biological metalloproteins in particular, and metals in biology in general (measured at cryogenic conditions).

Beam Lines: 6-2b LCLS

Techniques

  • Resonant Inelastic X-ray Scattering
  • X-ray Emission Spectroscopy
  • X-ray Raman Spectroscopy

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X-ray Fluorescence Imaging

X-ray fluorescence imaging utilizes the high brightness of SPEAR3 and focused beam generated by the uses of K-B optics, capillaries and apertures to study spatial distribution of elements in biological samples such as brain tissue. The imaging beam lines have the unique capability of combining spatial mapping with chemical and structural information of various elements through XAS (edges and EXAFS). The three beam lines are equipped with standardized instrumentation for seamless measurement across 2-30 eV energy range and 2-250 µm length scales.

Beam Lines: 2-3 10-2a 14-3b

Techniques

  • Variable energy x-ray fluorescence mapping
  • Micro-XANES imaging and tomography
  • Micro-EXAFS imaging

View details »



Support

The SSRL SMB group is directly responsible for the maintenance and operation of the biological spectroscopy beamlines. User support is provided at the technical, engineering and scientific level of data acquisition and analysis by experienced staff personnel.

Instrumentation

The SMB group maintains and operates standard and specialized in-hutch instrumentation for a variety of research programs. These include; cryostats for low-temperature measurements, detector systems serving dilute and concentrated samples and specialized instrumentation for tender-energy and single-crystal XAS measurements. Experimental details about beamlines and information about their specific capabilities are listed under each beamlines technical page.

An interactive interface of the monochromotor crystal glitch library can be found here

Monochromator Crystal Sets

Liquid nitrogen-cooled monochromators at SSRL have two permanently installed crystal sets each which users can request. The distribution of monochromator crystals has been planned such that the most appropriate crystal cuts are available for the most commonly requested energy ranges. Users cannot request crystals for LN2-cooled monochromators that are not one of the two options already installed. Bending magnet beam lines have water-cooled monochromators, that can be replaced on demand (BL2-3 and BL14-3).

Available crystal sets in LN2-cooled monochromators at SSRL:

  • BL7-3: Si(220)-phi=0 or Si(220)-phi=90
  • BL9-3: Si(220)-phi=0 or Si(220)-phi=90
  • BL4-3: Si(111)-phi=0 or Si(111)-phi=90
  • BL14-3: Si(111)-phi=0 or Si(111)-phi=90
  • BL6-2: Si(111)-phi=0 or Si(311)-phi=0
  • BL2-3: Si(111), Si(220),or Si(400) (water-cooled)
  • BL10-2: Si(111)-phi=90 or Si(220)-phi=90

Software

The data collection softwares used on the spectroscopy beamlines include XASCollect and XASSCAN. Beamline computers are also equipped with the data analysis softwares EXAFSPAK and SixPACK.

Research

The next steps after successful data measurement at the experimental station are data reduction, analysis and simulation. SSRL staff provides training and support for in-house data analysis software for preliminary data-analysis and the SMB group organizes annual Summer Schools for training in advanced experimental data analysis. In addition, several web-based resources are available for additional and specialized information.

The research conducted at the bio-spectroscopy beamlines follows the mission of NIH and DOE-BER and is aimed at elucidating the geometric and electronic structure of metalloprotein and cofactor active sites and biomimetic model complexes in order to shed light on the mechanistic aspects of relevant biological systems. High-impact publications from the bio-spectroscopy beamlines are routinely highlighted by SSRL. See more.