Building off technologies and expertise developed in the Synchrotron X-ray Absorption Spectroscopy project, the Spectroscopic Imaging effort seeks to develop measurements that provide spatial mapping of the local chemical, electronic, and physical structure in advanced materials. Technology is developed as part of the NIST BNL partnership at the National Synchrotron Light Source II in Upton, NY. Specific goals of the project are to develop beamline optics, instrument configurations, sample environments, and detector technologies that provide spatially resolved spectrums that support needs in device characterization, process optimization, and samples with inherent spatial inhomogeneity. These efforts often build off of data processing, reduction, and modelling platforms developed for the spectrometers. Testing and identification of future needs is accomplished through engagement of NIST staff, stakeholders, and the general user program at NSLS-II.
Of the nine end stations in designed and operated by NIST, three are dedicated for spatial spectroscopic imaging. As with spectrometers that measure a spatial average of an entire sample, a sample is exposed to an incident X-ray beam and the emission products of electronic excitation and resulting decay are measured. Instead of a sample spanning average, these techniques attempt to employ magnetic environments that shuttle the emission products to a spatially resolved detector.
The imaging effort has been developed through the use of the NIST Small Business Innovation and Research (SBIR) grant program, resulting in longstanding efforts with Synchrotron Research and R. Browning Consultants. Here, the innovation has resulted in the first NEXAFS microscope system, the Large Area Rapid Imaging Tool (LARIAT MK I), that was designed, installed, and brought into successful use at the previous facility, NSLS-I. The LARIAT system features a large effective numerical aperture, and a nearly perfect efficiency in electron transport to the detector, with relatively high speeds for image collection (on the order of 30 images/minute at 7 micron resolution. Using a energy resolved detection system, the images are hyperspectral, providing a full spectrum within each spatial pixel. The move to NSLS-II includes the successful development of the LARIAT MK II, which utilizes a supermagnet to lens with higher efficiency and spatial resolution, providing the next step in this successful project.
The Vector Potential Photoelectron Microscope (VPPEM) is also bringing its second phase to NSLS-II, building off of a prototype tested at NSLS-I. This technique converts the photoelectron momentum into spatial vectors, resulting in a new method of image construction. Still in the early stages of development, the full impact of VPPEM is yet to be realized.
LARIAT MK I - The Large Area Rapid Imaging Tool, Mark I
LARIAT MK II - The Large Area Rapid Imaging Tool, Mark II
VPPEM - The Vector Potential Photoelectron Microscope