Shining Synchrotron Light on Supercritical Fluids Alan J. Anderson St. Francis Xavier University

The Hydrothermal Diamond Anvil Cell HDAC

Hydrothermal Diamond Anvil Cell (HDAC)

Grooves Sample Chamber Re Gasket Different Diamond Anvil Configurations

Surface Profilometry Average depth μm Volume 3.55 X 10 6 µm 3 FIB Milling of Diamond Anvil

Aqueous solution Vapor bubble HDAC Sample Chamber at 25 o C 0.2 mm

Liquid Vapor Isochores ρ = 0.87

Synchrotron X-ray Micro- and Nanoprobes

Canadian Light Source Inc.

Detector

VaporLiquid Path of Incident X-rays Path of Fluorescence X-rays to the Detector Solution in Sample 25 ºC 300 µm Diamond Anvil

X-ray Fluorescence Imaging and Quantitative Analysis

Map showing the distribution of Ta 2 O 5 particles in 5% HF at 25 ºC (HDAC 116) Map showing the distribution of Ta in 5% HF at 360°C (HDAC 116) Solid Ta 2 O 5 Particles 100 µm

Ta 2 O 5 Dissolved in 5% HF HDAC 360°C (ρ = 0.566) 10,700 μg mL -1 Ta HDAC 350°C (ρ = 0.575) 7,400 µg mL -1 Ta Ta Standard (1000 µg mL -1 ) HDAC 360°C (ρ = 0.575) HDAC 400°C (ρ = 0.504) Ta L β1 Fe K β1 Fe K α1 Ta L α1 Energy (keV) Intensity

Time resolved analysis - Pb in aqueous fluid during interaction with partially metamict zircon (ZrSiO 4 ) at 300 o C

X-ray Absorption Spectroscopy XAS Resolving the local structure of metals in SCW

X-ray Absorption Fine Structure (XAFS)

Summary Synchrotron – based techniques Monitor SCW – material interaction Resolve the local structure of aqueous metal complexes Solubility of selected oxides

Raman spectroscopy Raman system HDAC on the microscope

Energy (keV) Re L lines Ta L lines Interferences in X-ray Emission Spectra

Energy (keV) Counts Sample Contamination from Re Gasket

CH 4 Sample Contamination from Gasket Reaction with Diamond

X-ray Diffraction

In situ XRD Wu et al. (1997) Dehydration & Rehydration of Montmorillonite Reversible changes in lattice dimensions