Raman spectroscopic study of the uranyl tellurite mineral moctezumite PbUO 2 (TeO 3 ) 2

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The mixed anion mineral chalcophyllite Cu 18 Al 2 (AsO 4 ) 4 (SO 4 ) 3 (OH) 24 ·36H 2 O has been studied by using Raman and infrared spectroscopies. Characteristic bands associated with arsenate, sulfate and hydroxyl units are identified. Broad bands in the OH stretching region are observed and are resolved into component bands. Estimates of hydrogen bond distances were made using a Libowitzky function. Both short and long hydrogen bonds were identified. Two intense bands at 841 and ∼814 cm −1 are assigned to the ν 1 (AsO 4 ) 3− symmetric stretching and ν 3 (AsO 4 ) 3− antisymmetric stretching modes. The comparatively sharp band at 980 cm −1 is assigned to the ν 1 (SO 4 ) 2− symmetric stretching mode, and a broad spectral profile centred upon 1100 cm −1 is attributed to the ν 3 (SO 4 ) 2− antisymmetric stretching mode. A comparison of the Raman spectra is made with other arsenate-bearing minerals such as carminite, clinotyrolite, kankite, tilasite and pharmacosiderite.

Section: Introductionmentioning

confidence: 99%

Raman spectroscopic study of the hydroxy‐arsenate‐sulfate mineral chalcophyllite Cu₁₈Al₂(AsO₄)₄(SO₄)₃(OH)₂₄·36H₂O

Frost

Palmer

Keeffe

2010

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“…The aim of this paper is to report the Raman spectra of geminite samples of different origin, and to relate the spectra to the molecular and crystal chemistry of (AsO 3 OH) 2− ions containing arsenate type mineral. The paper follows the systematic research of the large group of supergene minerals,7–9 and especially molecular structure of minerals containing oxyanions using Raman and infrared spectroscopies 10–29…”

Section: Introductionmentioning

confidence: 99%

Raman spectroscopy of hydrogen‐arsenate group (AsO₃OH) in solid‐state compounds: copper mineral phase geminite Cu(AsO₃OH)·H₂O from different geological environments

Sejkora¹,

Čejka²,

Frost³

et al. 2009

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The participation of hydrogen-arsenate group (AsO 3 OH) 2− in solid-state compounds may serve as a model example for explaining and clarifying the behaviour of As and other elements during weathering processes in natural environment. The mineral geminite, a hydrated hydrogen-arsenate mineral of ideal formula Cu(AsO 3 OH)·H 2 O, has been studied by Raman and infrared spectroscopies. Two samples of geminite of different origin were investigated and the spectra proved quite similar. In the Raman spectra of geminite, six bands are observed at 741, 812, 836, 851, 859 and 885 cm −1 (Salsigne, France), and 743, 813, 843, 853, 871 and 885 cm −1 (Jáchymov, Czech Republic). The band at 851/853 cm −1 is assigned to the ν 1 (AsO 3 OH) 2− symmetric stretching mode; the other bands are assigned to the ν 3 (AsO 3 OH) 2− split triply degenerate antisymmetric stretching mode. Raman bands at 309, 333, 345 and 364/310, 333 and 345 cm −1 are attributed to the ν 2 (AsO 3 OH) 2− bending mode, and a set of higher wavenumber bands (in the range 400-500 cm −1 ) is assigned to the ν 4 (AsO 3 OH) 2− split triply degenerate bending mode. A very complex set of overlapping bands is observed in both the Raman and infrared spectra. Raman bands are observed at 2289, 2433, 2737, 2855, 3235, 3377, 3449 and 3521/2288, 2438, 2814, 3152, 3314, 3448 and 3521 cm −1 . Two Raman bands at 2289 and 2433/2288 and 2438 cm −1 are ascribed to the strong hydrogen bonded water molecules. The Raman bands at 3235, 3305 and 3377/3152 and 3314 cm −1 may be assigned to the ν OH stretching vibrations of water molecules. Two bands at 3449 and 3521/3448 and 3521 cm −1 are assigned to the OH stretching vibrations of the (AsO 3 OH) 2− units. The lengths of the O-H· · ·O hydrogen bonds vary in the range 2.60-2.94 Å (Raman) and 2.61-3.07 Å (infrared). Two Raman and infrared bands in the region of the bending vibrations of the water molecules prove that structurally non-equivalent water molecules are present in the crystal structure of geminite.

“…The system was calibrated using the 520.5 cm −1 line of a silicon wafer. Further details have been published elsewhere 16–29. Alignment of all crystals in a similar orientation has been attempted and achieved.…”

Section: Methodsmentioning

confidence: 99%

Raman spectroscopic study of the mineral gerstleyite Na₂(Sb,As)₈S₁₃·2H₂O and comparison with some heavy‐metal sulfides

Frost

Bahfenne

Keeffe

2010

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The mineral gerstleyite is described as a sulfosalt as opposed to a sulfide. This study focuses on the Raman spectrum of gerstleyite Na 2 (Sb,As) 8 S 13 ·2H 2 O and makes a comparison with the Raman spectra of other common sulfides including stibnite, cinnabar and realgar. The intense Raman bands of gerstleyite at 286 and 308 cm −1 are assigned to the SbS 3 E antisymmetric and A 1 symmetric stretching modes of the SbS 3 units. The band at 251 cm −1 is assigned to the bending mode of the SbS 3 units. The mineral stibnite also has basic structural units of Sb 2 S 3 and SbS 3 pyramids with C 3v symmetry. Raman bands of stibnite Sb 2 S 3 at 250, 296, 372 and 448 cm −1 are assigned to Sb-S stretching vibrations and the bands at 145 and 188 cm −1 to S-Sb-S bending modes. The Raman band for cinnabar HgS at 253 cm −1 fits well with the assignment of the band for gerstleyite at 251 cm −1 to the S-Sb-S bending mode. Raman bands in similar positions are observed for realgar AsS and orpiment As 2 S 3 .