These techniques are used to study the energies of particles that are emitted or absorbed by samples that are exposed to the light-source beam and are commonly used to determine the characteristics of chemical bonding and electron motion.
In spectroscopy experiments, a sample is illuminated with light and the various product particles (electrons, ions, or fluorescent photons) are detected and analyzed. The unifying feature is that some “property” of a material is measured as the x-ray (photon) energy is swept though a range of values. At the most basic level, one measures the absorption, transmission, or reflectivity of a sample as a function of photon energy.
Probes that use the vacuum ultraviolet (VUV) region of the spectrum (10–100 eV) are very well matched to the elucidation of bonding in solids, surfaces, and molecules; to the investigation of electron–electron correlations in solids, atoms, and ions; and to the study of reaction pathways in chemical dynamics. At the lowest end of this energy range (below 1 eV) we have infrared, far-infrared, and terahertz spectroscopies, which are well matched to vibrational modes and other modes of excitation.
Soft x-ray spectroscopies employ the excitation of electrons in relatively shallow core levels (100–2000 eV) to probe the electronic structure of various kinds of matter. Elemental specificity is the watchword for this kind of spectroscopy. Each element has its own set of core levels that occur at characteristic energies. The photon-energy tunability of synchrotron radiation is essential.
Hard x-ray spectroscopy is applied in a wide variety of scientific disciplines (physics, chemistry, life sciences, and geology) to investigate geometric and electronic structure. The method is element-, oxidation-state-, and symmetry-specific. It is a primary tool in the characterization of new and promising materials. It is also used in the elucidation of dilute chemical species of environmental concern.
Beamline 15-2 is an undulator experimental station dedicated to advanced hard x-ray spectroscopy. The end station is equipped with sub-corehole lifetime resolution x-ray emission spectrometers (a 7-crystal Johann spectrometer and a 8 crystal von Hamos instrument) as well as a high-throughput and high energy resolution (0.3eV) 40-crystal low-q x-ray Raman spectrometer.
Beam line 14-3b, located on the downstream table in the BL14-3 hutch, is a bending magnet side station dedicated to x-ray imaging and micro x-ray absorption spectroscopy of biological, biomedical, materials, and geological samples. Most often used for data collection at the S K edge, BL14-3 is the only SSRL beam line capable of XAS at the P K edge. During imaging mode, a SIGRAY axially symmetric mirror system is used to achieve the microfocus with a beam size of ~ 5 x 5 microns, or sub-micron sizes.
Beam line 14-3a, located on the upstream table of the hutch of the BL14-3 bending magnet side station, is dedicated to bulk x-ray absorption spectroscopy of biological, materials, and geological samples in the tender x-ray photon energy range 2.1-5.0 keV. BL14-3 is the only beam line at SSRL capable of obtaining spectroscopy data at the phosphorous K edge. In this configuration the beam is unfocused over a size of 1 mm x 6 mm to allow for high energy-resolution measurements on homogenous samples.
Beam line 13-3 utilizes a spherical grating monochromator (SGM) on an elliptical polarized undulator (EPU) operating in the photon energy range from 230 eV to 1700 eV with full polarization control (linear vertical/horizontal and circular left/right) covering the C, O, F K-edges, 3d transition metal L-edges, and 4f rare-earth element M-edges.
Beam line in transition.
Beam line 11-2 is a high-flux XAS station dedicated to molecular biogeochemical and interface sciences. It is optimized for challenging XAS measurements on dilute or radioactive samples and interfaces. To support these experiments, BL11-2 is equipped with collimating and focusing optics, a "double double" Si(220) LN2-cooled monochromator, and a 100-pixel monolithic solid state Ge detector array.
Beam line currently closed for upgrade.
Beam line 10-2 is a wiggler-based source that splits time between the front hutch (BL10-2a), instrumented for wide-angle X-ray scattering, and the rear hutch (BL10-2b), instrumented for X-ray spectroscopy with a focus on in-situ, time-resolved catalyst characterization.
Beam line 9-3 is a wiggler side-station dedicated to biological x-ray absorption spectroscopy and EXAFS measurements of dilute solutions and single crystals. BL9-3 is equipped with a 100-element Ge monolithic solid-state detector in addition to ionization chambers and PIPS/Lytle detectors. A dedicated LHe cryostat allows for routine low temperature measurements on solutions. A Huber-Kappa goniometer, a LHe cryostream, a focusing polycapillary and a MAR CCD detector are available (in addition to specialized software) for single crystal measurements.
Beam line 9-2 is a wiggler end station dedicated for monochromatic, high-throughput and high-resolution macromolecular crystallography and optimized for SAD and MAD experiments. It can be run in a full remote access mode. It is equipped with a Dectris Pilatus 6M PAD detector and a remote access controlled UV-Vis microspectrophotometer.
See the Macromolecular Crystallography website for details.
Beam line 8-2 can be used to probe a wide range of core levels using photoemission and x-ray absorption spectroscopies. At BL 8-2, currently only one end-stations is available for the general user program. The first end-station is a high throughput setup for soft x-ray spectroscopy measurement – upgrades in progress include a fixed position multipurpose chamber with a load lock system for high throughput sample loading, capable of probing a wide range of materials with absorption and photoemission techniques.