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Observation of bicarbonate in calcite by NMR spectroscopy

Jian Feng, Young J. Lee, Richard J. Reeder and Brian L. Phillips
Observation of bicarbonate in calcite by NMR spectroscopy
American Mineralogist (May 2006) 91 (5-6): 957-960

Abstract

We show that the signal observed in (super 13) C{ (super 1) H} cross-polarization magic-angle-spinning (CP/MAS) NMR spectra of synthetic calcite precipitated at room temperature arises from bicarbonate ion. Although this peak occurs at the same chemical shift as for the bulk carbonate signal, its observation by CP/MAS indicates that it corresponds to carbonate associated with H. The variation in the CP/MAS intensity with contact time shows oscillations characteristic of C-H pairs separated by 1.9(1) Aa and remote from other H, consistent with bicarbonate. (super 13) C{ (super 1) H} heteronuclear correlation spectra indicate that the hydrogen in the bicarbonate groups gives a relatively narrow (super 1) H NMR signal at +7.4 ppm. A peak at this chemical shift is also observed in direct-observe (super 1) H MAS NMR spectra of the synthetic sample, and also in natural biogenic and abiogenic calcite. This (super 1) H chemical shift indicates a moderate hydrogen bonding interaction d(OH...O) nearly equal 1.85 Aa, which suggests significant structural relaxation occurs near the bicarbonate.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 91
Serial Issue: 5-6
Title: Observation of bicarbonate in calcite by NMR spectroscopy
Affiliation: State University of New York, Department of Chemistry, Stony Brook, NY, United States
Pages: 957-960
Published: 200605
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 26
Accession Number: 2006-053789
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200615
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