Calculated trends of oh infrared stretching vibrations with composition and structure in aluminosilicate molecules

Abstract

Abstract. Ab initio, molecular orbital calculations have been performed on a variety of hypothetical aluminosilicate molecules to investigate relationships among composition, structure, and infrared spectra of OH. Vibrational analyses of the full-optimized molecular geometries at the 3-21G** level were performed with Gaussian 92 to determine theoretical infrared spectra. Theoretical infrared OH frequencies, ~(OH), shift 10 to 100 cm -1 with ionic substitutions. The inverse correlation of theoretical infrared OH intensities with OH stretching frequencies in these aluminosilicate molecules is similar to that observed for aluminosilicate glasses

IR absorption coefficients for water in nominally anhydrous high-pressure minerals

“…The molar absorption coefficient ε can be given as the linear absorption coefficient in L/mol(H 2 O)/cm -1 using the peak height as measure for the absorption or as the integral absorption coefficient ε i [in L/mol(H 2 O)/cm -2 ] when the area under the corresponding OH bands is considered 1 . Figure 1a shows the trend for absorption coefficients ε i for water in hydrous minerals and glasses vs. the wavenumber of the corresponding OH-bands as determined experimentally by Paterson (1982) and Libowitzky and Rossman (1997), and as calculated theoretically in the studies of Kubicki et al (1993) and Balan et al (2008). There is no doubt about the general trend, i.e., that ε increases with decreasing wavenumber.…”

“…Thomas et al (2009) discussed how ε-values for NAMs cannot be estimated using the general calibration Paterson (1982) and Libowitzy and Rossman (1997) and as calculated in theoretical studies by Kubicki et al (1993) and Balan et al (2008); in respect to the correlations by Paterson (1982) and Libowitzy and Rossman (1997), only the idealized trends are shown for simplicity-in reality the data scatter a bit around these trends. (b) Comparison of the general trend of ε-values for water in hydrous minerals and glasses vs. wavenumbers of the corresponding OH bands as determined experimentally by Libowitzy and Rossman (1997) with ε-values for NAMs from literature and for Fe-Mg ringwoodite determined in this study.…”

Study on the Disposition of Water in Fly Ash-Based Geopolymers Using ATR–IR

“…This means that both heat and ethanol affect the appearance of the regions and intensity of these OH stretching vibrations, and, evidently heat has greater ability of eliminating these OH groups because these two peaks are still evident in 7-ER-E but much weaker in 7-ERD. Further, the fact that Al … O-H stretching has also been observed in the same region (Kubicki, Sykes, & Rossman, 1993) suggests that these vibrations are probably contributed to hydrogen bond of Al-OH and sodium ions that are in the pore solution. These two peaks are unlikely to be Ca-OH correlated [the OH groups in Ca(OH) 2 are not considered to be hydrogen bonded], as cement product, such as tobermorite, calcium aluminosilicate, and jennite, seem to have OH stretching band in a lower region (3624-3100 cm -1 ) (Yu, Kirkpatrick, Poe, McMillan, & Cong, 1999).…”

“…It has a smaller O-H … O distance (3.137 Å) than that in sodium-correlated OH stretching, attributed to the substitutions of cation that is bonded to an OH group, which can cause a shift in the frequency by a magnitude of 100 cm -1 in aluminosilicates (Kubicki, Sykes, & Rossman, 1993). The aforementioned regions are probably a result of the hydrogen bonds in the structures, such as Na + (OH) 2 Al-O-Si, in geopolymers' pore solution, as they are very weak and nearly absent in samples that are dried using heat, such as 7-ERD, 7-ER-ED, and G-105.…”

Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex—Electronic structure, vibrational frequencies, and equilibrium Fe-isotope fractionation

“…Frequencies are listed in cm À1 . Intensities are listed in cm À2 /mol/ L, converted from km/mol using a factor of 100 (Kubicki et al, 1993). The calculations from were for an uncomplexed model, and those from this study are for the Fe(III)-DFO-B complex.…”