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A High-Pressure NMR Probe for Aqueous Geochemistry

Authors


  • This work is supported by the Department of Energy grant DE-FG02-05ER15693 and by LLNL under Contract DE-AC52-07NA2734 LLNL-JRNL-654755. Additional funding sources and awknowledgements are listed in the Supporting Information.

Abstract

A non-magnetic piston-cylinder pressure cell is presented for solution-state NMR spectroscopy at geochemical pressures. The probe has been calibrated up to 20 kbar using in situ ruby fluorescence and allows for the measurement of pressure dependencies of a wide variety of NMR-active nuclei with as little as 10 μL of sample in a microcoil. Initial 11B NMR spectroscopy of the H3BO3–catechol equilibria reveals a large pressure-driven exchange rate and a negative pressure-dependent activation volume, reflecting increased solvation and electrostriction upon boron-catecholate formation. The inexpensive probe design doubles the current pressure range available for solution NMR spectroscopy and is particularly important to advance the field of aqueous geochemistry.

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