The concentration and speciation of hydrogen in feldspars using FTIR and ^1H MAS NMR spectroscopy
- Johnson, Elizabeth A.
- Rossman, George R.
DOIAbstract
A universal absorption coefficient was determined for quantitative analysis of OH and H_2O in feldspars using infrared spectroscopy. ^1H MAS (magic-angle spinning) NMR spectroscopy was used to determine the H concentration in three alkali feldspars, and for the first time, eight plagioclase samples. To accurately measure structural H concentration in samples with low H (<1000 ppm H_2O) it was necessary to eliminate the signal due to adsorbed water in the powdered NMR sample. The pegmatitic and metamorphic albite samples are transparent, but contain variable (40–280 ppm H_2O) concentrations of microscopic to sub-microscopic fluid inclusions. The pegmatitic albites also have sharp bands in the mid-IR similar to the OH bands found in quartz. T...
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