Development of a Tender-Energy Microprobe for Geosciences at NSLS and NSLS-II

Abstract

We propose to develop a tender-energy (1-8 keV operational range, optimized for 1-5 keV) X-ray microprobe, to bring the functionality and scientific benefits of hard (>5 keV) X-ray microprobes to a largely untapped domain of lighter, geologically-important elements. This proposal seeks to extend and enhance user-facility capabilities particularly optimized for research in Geosciences. This will be accomplished through development and implementation of unique new synchrotron instrumentation for high-performance microspectroscopy and imaging in the distinctive tender energy range. This new user facility at Beamline X15B at the National Synchrotron Light Source (NSLS) will benefit the specific Earth Science research programs described in this proposal, and will be available for use by the broader community through the merit-based General User program and through the User Cooperative that operates X15B. Its development will provide immediate benefit to regional and national Earth Science research conducted at the NSLS. It will achieve even higher performance at the Tender Energy Spectroscopy (TES) Beamline at NSLS-II, a new state-of-the-art synchrotron under construction and scheduled to begin operation in 2014. Project Objectives: Our goals are threefold: 1. Develop superlative capabilities to extend hard X-ray microprobe functionality and ease of use to the tender energy range. 2. Bring high-performancemore » XAS (including full EXAFS) to the micron scale, over the range of 1-8 keV. 3. Deliver high flux and element sensitivity for geoscience applications. Our user facility will be designed and optimized for tender-energy microbeam applications and techniques for Earth Science research, including XRF imaging and high-quality extended XAS. Its key attributes will be an energy range of 1 to 8 keV, user-tunable spot size ranging from 40x14 to 3x2 μm, high flux up to 2x1011 photons/s, beam positional stability and energy calibration stability optimized for high-quality and extended XAS and both XRF and XAS imaging, a helium sample environment for vacuum-incompatible samples, and on-the-fly scanning. At NSLS-II, these capabilities will be further enhanced and performance will improve in spot size, to the range from 19x23 to <1x1 μm, and flux, up to 1012 ph/s. Thus the proposed microprobe will deliver much of the versatility and ease of use of hard Xray KB microprobes (sample accommodation, minimal sample preparation requirements, wet or in-situ measurements, etc.), plus capabilities for high quality and rapid EXAFS at microbeam spatial resolution. Specific new capabilities proposed here are: 1. Tender-energy XRF imaging of Na to Co, utilizing their K fluorescence lines, Cu to Ho by their L lines, and the Pr to Pu M lines. 2. Microbeam and singleparticle XANES and EXAFS over the energy range for Mg to Co K edges, Ge to Ho L3 edges, and Tb to Pu M5 edges. 3. XAS speciation imaging in several “step-” and “on-the-fly-” scanning modes. 4. Usertunable spatial resolution from microbeam to mm scales. Concentrating on development of the core microfocusing capabilities at X15B will result in a very high and immediate impact on Earth Science microprobe research at NSLS. This proposal will enable collection of publishable tender-energy microbeam data within about 6 months, and strongly complement and enhance existing NSLS microprobe programs. Establishment of this user facility at NSLS X15B will ensure its transfer to the NSLS-II TES beamline and its earliest possible availability for Geoscience research. This is essential for continuity of user science programs across the transition from NSLS to NSLS-II, to ensure their productivity early in the start-up of NSLS-II. Ultimately, the proposed facility will provide unique new microspectroscopic capabilities that currently do not exist elsewhere.« less