Investigation of silicate mineral sanidine by vibrational and NMR spectroscopic methods.
Sanidine, a variety of feldspar minerals has been investigated through optical absorption, vibrational (IR and Raman), EPR and NMR spectroscopic techniques. The principal reflections occurring at the d-spacings, 3.2892, 3.2431, 2.9022 and 2.6041 A confirm the presence of sanidine structure in the mineral. Sanidine shows five prominent characteristic infrared absorption bands in the region 1200-950, 770-720, 590-540 and 650-640 cm(-1). The Raman spectrum shows the strongest band at 512 cm(-1) characteristic of the feldspar structure, which contains four membered rings of tetrahedra. The UV-vis-NIR absorption spectrum had strong absorption features at 6757, 5780 and 5181 cm(-1) due to the combination of fundamental OH- stretching. The bands at 11236 and 8196 cm(-1)and the strong, well-defined band at (30303 cm(-1) attest the presence of Fe(2+) and Fe(3+), respectively, in the sample. The signals at g = 4.3 and 3.7 are interpreted in terms of Fe(3+) at two distinct tetrahedral positions Tl and T2 of the monoclinic crystal structure The (29)Si NMR spectrum shows two peaks at -97 and -101 ppm corresponding to T2 and T1, respectively, and one peak in (27)Al NMR for Al(IV).
Anbalagan
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G
Department of Physics, Presidency College, Chennai 600005, India. anbu24663@yahoo.co.in
Sankari
G
G
Ponnusamy
S
S
Kumar
R Thilak
RT
Gunasekaran
S
S
D009682:Magnetic Resonance Spectroscopy; D017640:Silicates / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
D017640:Silicates; C545846:sanidine