Beam Line 6-2b X-ray Emission Spectroscopy
Beam Line 6-2b is an advanced spectroscopy experimental station on the multidisciplinary general user wiggler Beam Line 6 dedicated to X-ray spectroscopy techniques over 5 – 30 KeV. The techniques include X-ray Emission Spectroscopy (XES), Resonant Inelastic X-ray Scattering (RIXS), High Energy Resolution Fluorescence Detection (HERFD) and X-ray Raman Spectroscopy (XRS). Scientific applications are in Structural Biology, Chemical Catalysis and Materials and Environmental Sciences.
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).
Resonant inelastic x-ray scattering (RIXS) is a spectroscopic technique, which uses monochromatic incident and emitted fluorescent x-rays to create a 2p-3d core emission spectral intensity map, which holds electronic information simultaneously about the bound and valence energy levels of the absorbing atom, although the information is distinct from that obtained from the individual absorption and emission processes involved in RIXS. Beamline 6-2b is equipped with a cryostat to perform RIXS on sensitive biological systems.
The X-ray absorption near-edge region holds subtle electronic structure information about orbital splitting, spin and oxidation states. However, standard x-ray absorption spectra are broadened due to the large finite lifetime of the core hole, much broader than that of the valence levels being probed. Using only a single fluorescence line with energy resolution better than the core hole life time results in the measurement of high-resolution fluorescence detected XANES spectra. This technique is especially important for high Z element with large core hole life times. Beamline 6-2b is equipped with analyzer crystals that allow for HERFD measurements on biological systems.
(XRS) is the non-resonant inelastic scattering of x-rays from core electrons. It is analogous to Raman scattering, which is a widely used tool in optical spectroscopy, with the difference being that the wavelengths of the exciting photons fall in the x-ray regime and the corresponding excitations are from deep core electrons. XRS is an element-specific spectroscopic tool for studying the electronic structure of matter. In particular, it probes the excited-state density of states (DOS) of an atomic species in a sample. On 6-2b XRS is used as a powerful hard x-ray method to probe the soft x-ray region without the constraints of vacuum environment.
The SSRL SMB group is directly responsible for the maintenance and operation of the advanced spectroscopy experimental station of beamline 6-2. User support is provided at the technical, engineering and scientific level of data acquisition and analysis by experienced staff personnel.