Quantitative analysis of H2O and CO2 in cordierite using polarized FTIR spectroscopy

摘要: We report a FTIR (Fourier transform infrared) study of set cordierite samples from different occurrence and with H2O/CO2 content. The specimens were fully characterized by combination techniques including optical microscopy, single-crystal X-ray diffraction, EMPA (electron microprobe analysis), SIMS (secondary ion mass spectrometry), spectroscopy. All cordierites are orthorhombic Ccmm. According to the data, Si/Al ratio is always close 5:4; X Mg ranges 76.31 96.63, additional octahedral constituents occur in very small amounts. Extraframework K Ca negligible, while Na reaches values up 0.84 apfu. shows H2O 1.52 CO2 1.11 wt%. Optically transparent single crystals oriented using spindle stage examined micro-spectroscopy under polarized light. On basis polarizing behaviour, observed bands assigned water molecules two orientations structural channels. IR spectra also show presence amounts CO samples. Refined integrated molar absorption coefficients calibrated for quantitative microanalysis both based on polarized-light For type I II (ν3 modes) calculated separately [I]e = 5,200 ± 700 l mol−1 cm−2 [II]e = 13,000 ± 3,000 l mol−1 cm−2, respectively. coefficient $$ \varepsilon_{{{\text{CO}}_{ 2} }} $$  = 19,000 ± 2,000 l mol−1 cm−2.