The spectroscopic search for water in barite group sulfates

Laurence Hopkinson, Petra Kristova, Ken Rutt

Research output: Contribution to journalArticle

Abstract

This study examines the mid and near infrared spectra of a suite of natural and synthetic powdered 23 minerals of the isostructural barite mineral group. The mid-infrared (MIR) spectra are wholly 24 compliant with anhydrous high purity anglesite, celestine and barite. The complementary near-25 infrared (NIR) spectra contain bands at ca 1.9μm (5263cm−1) and ca 1.4μm (7140 cm−1) assigned to 26 the (H2O) v2 (antisymmetric stretch) + v3 (bending vibration) combination band and overtones of the 27 fundamental OH stretching modes respectively. Peak-fitting of the ca 4660-6000cm-1 region of 28 interest reveals four shoulders to the (H2O) (v2 + v3) combination which are systematically ordered 29 with respect to interstitial metal covalent radius: [PbSO4] (lowest wave number) → [SrSO4] → 30 [BaSO4] (highest wave number). These bands are assigned to (M2+−O−H) surface complexation of 31 water with the sulfates. It is further interpreted that the two good-to-perfect cleavages in the 32 mineral group with resultant variation in (M2+ - O - H) bond lengths accounts for the existence of the 33 four bands and explain why absorption strength at ca 1.91μm (5236cm-1) is not a reliable indication 34 of the overall abundance of water in sulfate minerals. Spectral interpretation within the vicinity of 35 the water combination ca 1.91μm (5236cm-1) is further complicated by the presence of a higher 36 wavenumber (v1 + 4v3) sulfate combination and the appearance of a band interpreted as the (5v3) 37 overtone of [SO42-]. The results are discussed in the light of these findings.
Original languageEnglish
Article number117577
Pages (from-to)1-19
Number of pages19
JournalSpectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
DOIs
Publication statusPublished - 11 Oct 2019

Fingerprint

Barium Sulfate
Barite
barite
Sulfates
Minerals
sulfates
Infrared radiation
minerals
Water
Sulfate minerals
infrared spectra
water
Bond length
Complexation
Stretching
harmonics
Metals
bending vibration
shoulders
cleavage

Keywords

  • Barium
  • Lead
  • Mid-infrared
  • Near-infrared
  • Strontium
  • Sulfates

Cite this

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title = "The spectroscopic search for water in barite group sulfates",
abstract = "This study examines the mid and near infrared spectra of a suite of natural and synthetic powdered 23 minerals of the isostructural barite mineral group. The mid-infrared (MIR) spectra are wholly 24 compliant with anhydrous high purity anglesite, celestine and barite. The complementary near-25 infrared (NIR) spectra contain bands at ca 1.9μm (5263cm−1) and ca 1.4μm (7140 cm−1) assigned to 26 the (H2O) v2 (antisymmetric stretch) + v3 (bending vibration) combination band and overtones of the 27 fundamental OH stretching modes respectively. Peak-fitting of the ca 4660-6000cm-1 region of 28 interest reveals four shoulders to the (H2O) (v2 + v3) combination which are systematically ordered 29 with respect to interstitial metal covalent radius: [PbSO4] (lowest wave number) → [SrSO4] → 30 [BaSO4] (highest wave number). These bands are assigned to (M2+−O−H) surface complexation of 31 water with the sulfates. It is further interpreted that the two good-to-perfect cleavages in the 32 mineral group with resultant variation in (M2+ - O - H) bond lengths accounts for the existence of the 33 four bands and explain why absorption strength at ca 1.91μm (5236cm-1) is not a reliable indication 34 of the overall abundance of water in sulfate minerals. Spectral interpretation within the vicinity of 35 the water combination ca 1.91μm (5236cm-1) is further complicated by the presence of a higher 36 wavenumber (v1 + 4v3) sulfate combination and the appearance of a band interpreted as the (5v3) 37 overtone of [SO42-]. The results are discussed in the light of these findings.",
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The spectroscopic search for water in barite group sulfates. / Hopkinson, Laurence; Kristova, Petra; Rutt, Ken.

In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 11.10.2019, p. 1-19.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The spectroscopic search for water in barite group sulfates

AU - Hopkinson, Laurence

AU - Kristova, Petra

AU - Rutt, Ken

PY - 2019/10/11

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N2 - This study examines the mid and near infrared spectra of a suite of natural and synthetic powdered 23 minerals of the isostructural barite mineral group. The mid-infrared (MIR) spectra are wholly 24 compliant with anhydrous high purity anglesite, celestine and barite. The complementary near-25 infrared (NIR) spectra contain bands at ca 1.9μm (5263cm−1) and ca 1.4μm (7140 cm−1) assigned to 26 the (H2O) v2 (antisymmetric stretch) + v3 (bending vibration) combination band and overtones of the 27 fundamental OH stretching modes respectively. Peak-fitting of the ca 4660-6000cm-1 region of 28 interest reveals four shoulders to the (H2O) (v2 + v3) combination which are systematically ordered 29 with respect to interstitial metal covalent radius: [PbSO4] (lowest wave number) → [SrSO4] → 30 [BaSO4] (highest wave number). These bands are assigned to (M2+−O−H) surface complexation of 31 water with the sulfates. It is further interpreted that the two good-to-perfect cleavages in the 32 mineral group with resultant variation in (M2+ - O - H) bond lengths accounts for the existence of the 33 four bands and explain why absorption strength at ca 1.91μm (5236cm-1) is not a reliable indication 34 of the overall abundance of water in sulfate minerals. Spectral interpretation within the vicinity of 35 the water combination ca 1.91μm (5236cm-1) is further complicated by the presence of a higher 36 wavenumber (v1 + 4v3) sulfate combination and the appearance of a band interpreted as the (5v3) 37 overtone of [SO42-]. The results are discussed in the light of these findings.

AB - This study examines the mid and near infrared spectra of a suite of natural and synthetic powdered 23 minerals of the isostructural barite mineral group. The mid-infrared (MIR) spectra are wholly 24 compliant with anhydrous high purity anglesite, celestine and barite. The complementary near-25 infrared (NIR) spectra contain bands at ca 1.9μm (5263cm−1) and ca 1.4μm (7140 cm−1) assigned to 26 the (H2O) v2 (antisymmetric stretch) + v3 (bending vibration) combination band and overtones of the 27 fundamental OH stretching modes respectively. Peak-fitting of the ca 4660-6000cm-1 region of 28 interest reveals four shoulders to the (H2O) (v2 + v3) combination which are systematically ordered 29 with respect to interstitial metal covalent radius: [PbSO4] (lowest wave number) → [SrSO4] → 30 [BaSO4] (highest wave number). These bands are assigned to (M2+−O−H) surface complexation of 31 water with the sulfates. It is further interpreted that the two good-to-perfect cleavages in the 32 mineral group with resultant variation in (M2+ - O - H) bond lengths accounts for the existence of the 33 four bands and explain why absorption strength at ca 1.91μm (5236cm-1) is not a reliable indication 34 of the overall abundance of water in sulfate minerals. Spectral interpretation within the vicinity of 35 the water combination ca 1.91μm (5236cm-1) is further complicated by the presence of a higher 36 wavenumber (v1 + 4v3) sulfate combination and the appearance of a band interpreted as the (5v3) 37 overtone of [SO42-]. The results are discussed in the light of these findings.

KW - Barium

KW - Lead

KW - Mid-infrared

KW - Near-infrared

KW - Strontium

KW - Sulfates

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U2 - 10.1016/j.saa.2019.117577

DO - 10.1016/j.saa.2019.117577

M3 - Article

SP - 1

EP - 19

JO - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

JF - Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

SN - 1386-1425

M1 - 117577

ER -