Lina Wang

Raman and infrared spectroscopic study of turquoise minerals

Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed.

A vibrational spectroscopic study of the silicate mineral harmotome – (Ba,Na,K)1-2(Si,Al)8O16⋅6H2O – A natural zeolite

The mineral harmotome (Ba,Na,K)1-2(Si,Al)8O16⋅6H2O is a crystalline sodium calcium silicate which has the potential to be used in plaster boards and other industrial applications. It is a natural zeolite with catalytic potential. Raman bands at 1020 and 1102 cm(-1) are assigned to the SiO stretching vibrations of three dimensional siloxane units. Raman bands at 428, 470 and 491 cm(-1) are assigned to OSiO bending modes. The broad Raman bands at around 699, 728, 768 cm(-1) are attributed to water librational modes. Intense Raman bands in the 3100 to 3800 cm(-1) spectral range are assigned to OH stretching vibrations of water in harmotome. Infrared spectra are in harmony with the Raman spectra. A sharp infrared band at 3731 cm(-1) is assigned to the OH stretching vibration of SiOH units. Raman spectroscopy with complimentary infrared spectroscopy enables the characterization of the silicate mineral harmotome.

A Raman and infrared spectroscopic study of the sulphate mineral aluminite Al2(SO4)(OH)4·7H2O.

The mineral aluminite has been studied using a number of techniques, including scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Raman spectroscopy identifies multiple sulphate symmetric stretching modes in line with the three sulphate crystallographically different sites. Raman spectroscopy also identifies a low intensity band at 1069 cm(-1) which may be attributed to a carbonate symmetric stretching mode, indicating the presence of thaumasite. The observation of multiple bands in this ν4 spectral region offers evidence for the reduction in symmetry of the sulphate anion from Td to C2v or even lower symmetry. The Raman band at 3588 cm(-1) is assigned to the OH unit stretching vibration and the broad feature at around 3439 cm(-1) to water stretching bands. Water stretching vibrations are observed at 3157, 3294, 3378 and 3439 cm(-1). Vibrational spectroscopy enables an assessment of the molecular structure of aluminite to be made.

A Raman and infrared spectroscopic study of the phosphate mineral pseudolaueite and in comparison with strunzite and ferrostrunzite

The Raman spectra of pseudolaueite, strunzite, ferrostrunzite and ferristrunzite have been obtained at 298xa0K using Raman microscopy. These spectra are compared with their infrared spectra. The vibrational spectra of the four minerals are different, in line with differences in crystal structure and composition. Some similarity in the Raman spectra of the hydroxyl-stretching region exists, particularly but characteristic differences in the OH deformation regions are observed. Differences are also observed in the phosphate stretching and deformation regions.Graphical AbstractThis paper offers new knowledge and understanding of the mineral pseudolaueite of formula Mn2+Fe23+(PO4)2(OH)2·8H2O,a hydrated hydroxy phosphate of ferric iron and manganese.

SEM, EDX and Raman and infrared spectroscopic study of brianyoungite Zn3(CO3,SO4)(OH)4 from Esperanza Mine, Laurion District, Greece.

The mineral brianyoungite, a carbonate-sulphate of zinc, has been studied by scanning electron microscopy (SEM) with chemical analysis using energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Multiple carbonate stretching modes are observed and support the concept of non-equivalent carbonate units in the brianyoungite structure. Intense Raman band at 1056 cm(-1) with shoulder band at 1038 cm(-1) is assigned to the CO3(2-) ν1 symmetric stretching mode. Two intense Raman bands at 973 and 984 cm(-1) are assigned to the symmetric stretching modes of the SO4(2-) anion. The observation of two bands supports the concept of the non-equivalence of sulphate units in the brianyoungite structure. Raman bands at 704 and 736 cm(-1) are assigned to the CO3(2-) ν4 bending modes and Raman bands at 507, 528, 609 and 638 cm(-1) are assigned to the CO3(2-) ν2 bending modes. Multiple Raman and infrared bands in the OH stretching region are observed, proving the existence of water and hydroxyl units in different molecular environments in the structure of brianyoungite. Vibrational spectroscopy enhances our knowledge of the molecular structure of brianyoungite.