Beamline 10.3.2 at ALS: a hard X-ray microprobe for environmental and materials sciences

TLDR

Beamline 10.3.2 at the ALS is a bend‑magnet line that combines X‑ray fluorescence mapping, microspectroscopy, and micro‑XRD to study heavy‑metal speciation and location in environmental samples. Its optics, based on a Kirkpatrick–Baez mirror pair, allow users to trade a 5–17 µm spot size for flux in the 3–17 keV range, with continuous‑scan XRF mapping that eliminates step‑and‑repeat overhead. The beamline’s unique capabilities are illustrated by several scientific results presented in the study.

Abstract

Beamline 10.3.2 at the ALS is a bend-magnet line designed mostly for work on environmental problems involving heavy-metal speciation and location. It offers a unique combination of X-ray fluorescence mapping, X-ray microspectroscopy and micro-X-ray diffraction. The optics allow the user to trade spot size for flux in a size range of 5–17 µm in an energy range of 3–17 keV. The focusing uses a Kirkpatrick–Baez mirror pair to image a variable-size virtual source onto the sample. Thus, the user can reduce the effective size of the source, thereby reducing the spot size on the sample, at the cost of flux. This decoupling from the actual source also allows for some independence from source motion. The X-ray fluorescence mapping is performed with a continuously scanning stage which avoids the time overhead incurred by step-and-repeat mapping schemes. The special features of this beamline are described, and some scientific results shown.