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State-of-the-art X-ray material characterization available at CNSI at UCSB

Custom high-brightness small-angle X-ray scattering instrument measures weakly scattering samples, offers remote access

For a range of scientific fields, small-angle X-ray scattering (SAXS) enables researchers to study nanoscale structures while monitoring change over time or under different conditions. The technique can be deployed to characterize biomaterials and polymers, as well as proteins, nucleic acid assemblies, viruses, crystals within cells and more.

A new, custom-built SAXS system with unparalleled brightness — up to 100 times greater than standard setups — is now available to investigators through the BioPACIFIC MIP, an NSF-supported project uniting the California NanoSystems Institute nodes at UCSB and UCLA. The device can measure weakly scattering samples with fast turnaround time for results. Users can access the SAXS instrument in person on the UCSB campus or remotely with a sample submission service.

“Part of the reason we decided to build the instrument ourselves was because this combination of the brightest source and the best detector is not commercially available,” said Youli Li, a UCSB research physicist and the X-ray diffractionfacility director. “Additionally, building in the high-throughput capability to process samples rapidly allows us to serve a larger number of user groups.

“More important, in my mind, is that we can develop the instrument to meet the needs of possible future applications,” he added. “The focus of research can shift over time, and we want this tool to be adaptable. We don’t want to build a big, fancy, expensive tool to do just one thing.”

The system features a state-of-the-art liquid gallium X-ray source and a large-area pixel array detector, allowing users to elucidate structures between 1 nanometer and 1 micrometer without damage to samples. Data collection happens quickly thanks to the 4-megapixel detector’s single-photon sensitivity and active area five times larger than traditional SAXS detectors — increasing speed or sensitivity by a factor of 50.

With tunable beam-size and a suite of in-house designed sample cells, the device makes possible experiments that previously required a synchrotron facility. The beamline instrument is also equipped with in-situ stages for temperature- and flow-controlled studies.

Scientists and engineers probing thin films and the interfaces of nanostructured materials can benefit from grazing incidence SAXS, a method that exposes samples to the X-ray at an angle that is typically close to the critical angle for external reflection. The result is enhanced scattering from the surface of a sample down to a few nanometers thickness.

Access to the BioPACIFIC SAXS instrument at UCSB is available via user proposals or on a recharge basis. For general information, contact user coordinator Eleni Papananou, at hellen@ucsb.edu. For project consultation and proof of concept, contact Li at youli@ucsb.edu. Users in need of training and assistance should contact X-ray diffraction specialist Phillip Kohl at phillipkohl@ucsb.edu.