title: High spatial resolution quantitative imaging by cross-calibration using Laser Ablation Inductively Coupled Plasma Mass Spectrometry and Synchrotron micro-X-ray Fluorescence technique.
abstract: High spatial resolution, quantitative chemical imaging is of importance to various scientific communities, however high spatial resolution and robust quantification are not trivial to attain at the same time. In order to achieve microscopic chemical imaging with enhanced quantification  capabilities, the current study links the independent and complementary advantages of two micro-analytical techniques - Synchrotron Radiation-based micro X-ray Fluorescence (SR-microXRF) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). A cross-calibration approach  is established between these two techniques and validated by one experimental demonstration. In the presented test case, the diffusion pattern of trace level Cs migrating into a heterogeneous geological medium is imaged quantitatively with high spatial resolution. The one-dimensional line  scans and the two-dimensional chemical images reveal two distinct types of geochemical domains: calcium carbonate rich domains and clay rich domains. During the diffusion, Cs shows a much higher interfacial reactivity within the clay rich domain, and turns out to be nearly non-reactive in  the calcium carbonate domains. Such information obtained on the micrometer scale improves our chemical knowledge concerning reactive solute transport mechanism in heterogeneous media. Related to the chosen demonstration study, the outcome of the quantitative, microscopic chemical imaging contributes  to a refined safety assessment of potential host rock materials for deep-geological nuclear waste storage repositories.
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: Hao A O
authors.initials: HA
authors.lastname: Wang
authors.forename: Daniel
authors.initials: D
authors.lastname: Grolimund
authors.forename: Luc R
authors.initials: LR
authors.lastname: Van Loon
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Barmettler
authors.forename: Camelia N
authors.initials: CN
authors.lastname: Borca
authors.forename: Beat
authors.initials: B
authors.lastname: Aeschlimann
authors.forename: Detlef
authors.initials: D
authors.lastname: Günther