Scientific communities such as environmental sciences, life sciences, and material sciences have identified the need to develop analytical resources to advance the understanding of complex natural and engineered systems that are heterogeneous on the micron to nanometer scale. These needs for high intensity x-ray nanoprobes resulted in the commitment of the NSLS-II Project to build the Submicron Resolution X-ray (SRX) Spectroscopy beamline showing a unique combination of high spectral resolution over a very broad energy range and very high beam intensity in a sub-micrometer spot. NSLS-II will provide one of the best sources in the world for such an instrument. The research topics to be addressed require characterization of elemental abundances and speciation in samples that are heterogeneous at the sub-micrometer scale.
The design shows a canted undulator beamline that consists of two branches, each optimized to reach very high spatial resolution for a specific energy range. The first branch is optimized to access higher energy and is included in the initial scope of NSLS-II for the SRX beamline. It will access an energy range of E = 4.65 keV to E = 25 keV. Two sets of Kirkpatrick-Baez (KB) mirror optics will focus the beam creating either a sub-micrometer sized focal spot at high flux or a sub-100 nm spot at moderate flux. A swap between the two setups will be possible in a couple of minutes. The second branch, optimized for lower energies, accessing spectroscopic edges from E = 2 keV to E = 15 keV, will require additional funding to be completed. Zone plates (ZP) will be used as focusing optics for this branch, creating a focal spot below 30 nm.
The wide energy range covered by both branches will allow the scientific community to address a wide range of research topics, as absorption edges of a large number of elements can be reached with the SRX beamline, allowing elemental mapping as well as spectroscopy studies. The two branches are required to cover this large energy range without compromising the aim of combining X-ray spectroscopy and sub-micron spatial resolution in an optimal way.