• journal_title：American Mineralogist
• Contributor：Vladimir M. Khomenko ; Klaus Langer
• Publisher：Mineralogical Society of America
• Date：2005-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2005.1963
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：90
• issue：11-12
• firstpage：1913
• section：Letters

Polarized IR-absorption spectroscopy in the range 7000–1000 cm⁻¹ has been used to examine natural cordierites of different geological origin and chemical composition. In the literature there is much information on H₂O and CO₂, as channel constituents in cordierite, though no isotopic species of these molecules have been distinguished. We newly identify ¹²C¹⁶O₂, ¹³C¹⁶O₂, ¹²C¹⁶O¹⁸O, as well as ¹²C¹⁶O from the single-crystal polarized IR spectra. The vibrational parameters, the temperature behavior, and polarization dependence of the identified carbon oxide molecules were studied in the temperature range 80–700 K. The molecular axes of the CO₂ and CO species are parallel to the a-axis of cordierite crystals. Repeated spectral measurements after heating confirm the low mobility along the c-axis channels of CO₂ and CO molecules at temperatures below 700 K. On the other hand, vibrational frequencies of CO₂ and CO species obtained in this investigation are close to those of the vapor phases, suggesting that the molecules are loosely bonded in the large cavities of the silicate framework.