Optical Determinations of OH in Fused Silica

Dodd, D. M.; Fraser, David B.

doi:10.1063/1.1707952

Cited by 55 publications

(10 citation statements)

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“…Although other compositional variables (Shelby eta!., 1982) and an e 0 / e 3670 of 0·022 (Stolper, 1982a). The e 500 estimated in this way is significantly higher than a previously reported value of 1·751/mol-cm by Dodd & Fraser (1966) .…”

Section: Compositional Dependence Of£ 4500 and C 5200contrasting

confidence: 48%

An Experimental Study of Water and Carbon Dioxide Solubilities in Mid-Ocean Ridge Basaltic Liquids. Part I: Calibration and Solubility Models

Dixon

Stolper

Holloway

1995

Journal of Petrology

141

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INTRODUCTIONSu baerial magmas solidify at a pressure of -1 bar, but the pressure on submarine magmas ranges from near I bar to several hundred bars, depending on the water depth at which they erupt. Even over this small pressure range, the vesicularity and vesicle-gas composition of submarine magmas of constant bulk composition can change dramatically, reflecting the large differences in volume between gaseous a nd melt species, the large compressibility of the gas phase at these low pressures, and the increasing (but different) solubilities of all gaseous species with pressure in this pressure range. Thus, the well-known negative corr elation between eruption depth a nd vesicularity of subm arine magmas reflects the degassing of magmas at progressively lower pressures under conditions where the exsolving vapor is unable to escape fully from the m agma (e.g. Moore, 1965, (!) Oxford University Press 1995 1970Moore & Schilling, 1973). Likewise, the different solubilities of the major (e.g. C02, H20, S) and minor (e.g. rare gases) volatile species are expected (though not yet observed) to lead to a strong dependence of the composition of the vapor in the vesicles on depth (e.g. Moore, 1965Moore, , 1970Jambon et al., 1985;Gerlach, 1986; ]ambon et al., 1986; Zhang & Zindler, 1989; Bottinga & Javoy, 1990b). Similarly, it is thought that differing solubilities of oxidized and reduced gaseous species can result in systematic changes in the oxidation state of iron and sulfur in erupting magmas as a function of the degree and depth of degassing (e.g. Sa to, 1978;Mathez, 1984; Carmichael & G hiorso, 1986;Christie et al., 1986;Wallace & Carmichael, 1992;Nilsson & Peach, 1993). In view of the importance of the exsolution of a vapor phase from submarine magmas in . understanding their vesicle contents, their eruptive style, aspects of their chemistry, and ultimately the chemistry of the atmosphere and ocean (e.g. Javoy et al., 1982;Des Marais, 1985; Marty & ]ambon, 1987;Gerlach, 1989; Zhang & Zindler, 1989, it is surprising how little is known about the behavior of volatile components in these systems in the pressure range over which these magmas are erupted. For example, only recently has the solubility of carbon dioxide, the major component of vesicle gases in mid-ocean ridge basalt (MORB) (Killingley & Muenow, 1975;Moore et al., 1977;Delaney et al., 1978;]ambon & Zimmermann, 1987), been measured in MORB melt by experiment (Stolper & Holloway, 1988;Shilobreyeva & Kadik, 1989; Mattey, 1991; Pan et al., 1991 ;Pawley et al., 1992;Trull et al. , 1992) . Water is even more abundant than carbon dioxide in most MORB glasses, but we know of no measurements of the solubility of water in MORB liquids at eruptive conditions, although water solubilities have been measured at higher pressures ( 1-10 kbar) in other basaltic compositions (Khitarov et al., 1959;Hamilton et al., 1964;Kadik et al., 1971 ). Kadik et al. (1972} reported mixed C0 2 and H 2 0 solubilities in basaltic melts at 1-3 kbar, but their experiments did not extend to...

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Section: Compositional Dependence Of£ 4500 and C 5200contrasting

confidence: 48%

An Experimental Study of Water and Carbon Dioxide Solubilities in Mid-Ocean Ridge Basaltic Liquids. Part I: Calibration and Solubility Models

Dixon

Stolper

Holloway

1995

Journal of Petrology

141

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“…By contrast, it is shown here that the molar integrated absorption coefficient ε (ν+δ)OH of the (ν+δ) OH combination band does not vary with the nature and the concentration of silanol groups present on a given silica sample. Absorbance at maximum of this band has been already used by Dodd and Fraser 31 to determine the OH content of silica glasses. More recently, different authors such as Davis et al 32 or Carteret 33 have determined ε (ν+δ)OH by separated IR and TG experiments, but their results are quite different.…”

Section: Resultsmentioning

confidence: 99%

Quantification of Water and Silanol Species on Various Silicas by Coupling IR Spectroscopy and in-Situ Thermogravimetry

et al. 2009

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Five silica samples (four precipitated silicas provided by commercial suppliers and one with the MCM-41 structure) have been studied by infrared spectroscopy and by a homemade thermogravimetry-infrared spectrum (TG-IR) setup. The silanol amount, accessibility to water, and different alcohols, and the affinity to water of these various silicas were compared and quantified. TG-IR measurements allowed the precise determination of the integrated molar absorption coefficient of the (nu+delta)OH band, epsilon(nu+delta)OH=(0.16+/-0.01) cm micromol(-1). It is independent of the sample origin and the concentration of silanol groups on silicas. For the precipitated dried samples evacuated at room temperature, the silanol concentration COH varies between 3.6 and 7.0 mmol g(-1). It is 5.3 mmol g(-1) in the case of the MCM-41 sample. Exchange experiments with D2O, followed by back-exchanges with different alcohols (methanol, propan-2-ol, 2-methyl-propan-2-ol, and 3-ethyl-pentan-3-ol) have been followed by infrared spectroscopy. All of the silanols of the MCM-41 sample are accessible to water and alcohol molecules. By contrast, about 20% of the silanols in precipitated samples are not exchanged by D2O (internal silanols). Accessibility decreases with alcohol size; the main effect is relative to methanol. Taking into account the sample specific surface areas and the silanol accessibility to D2O, the surface silanol density of precipitated silicas is close to 8 OH per nm2, at maximum coverage. At variance, the silanol surface density of the MCM silica is much lower, 4 OH per nm2. The TG-IR setup has also been used to determine the amount of water adsorbed on silicas through the intensity of the deltaH2O band. It varies linearly with the concentration of adsorbed water, whatever the silica sample. The integrated molar absorption coefficient of two bands, epsilondeltaH2O=(1.53+/-0.03) cm micromol(-1) and epsilon(nu+delta)H2O=(0.22+/-0.01) cm micromol(-1), have been determined. The number of H2O molecules adsorbed per nm2 has been compared on the five samples under an equilibrium pressure of 13 hPa at room temperature. Taking into account the number of silanols accessible to D2O for each sample, the silica-water affinity has been defined by the H2O/(SiOHsurf) ratio. It is close to 0.8-0.9 for the precipitated samples but lower (0.7) in the case of the MCM one. This result is explained by the more important amount of isolated silanol groups presented by this sample.

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“…Since the fundamental stretching vibrations of hydroxyl groups are located in the wavenumber region from 3500 to 3800 cm −1 , the NIR spectra in the wavenumber region from 7000 to 8000 cm −1 yield the information about the overtones of vibrations of different hydroxyl groups . It is possible to obtain the analyzable (nonsaturated) NIR spectra even for silica gel monoliths with thickness of a few millimeters since the extinction coefficient of the first OH overtone vibrations (∼0.5 L mol −1 cm −1 ) is several hundred times smaller than that of the fundamental vibrations (∼80 L mol −1 cm −1 ) …”

Section: Resultsmentioning

confidence: 99%

Effect of Microscopic Structure and Porosity on the Photoluminescence Properties of Silica Gels

et al. 2008

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We have studied the photoluminescence (PL) characteristics of silica gels with different microscopic morphology, which are prepared by acid-and base-catalyzed hydrolysis of tetraethylorthosilicate in ethanol solution. All the gels show visible PL emission peaking at ∼420 nm after annealing the samples at ∼200 °C in air; however, the PL intensity and decay kinetics are strongly dependent on the microstructure and porosity of the initial gels. The annealing-induced PL intensity increases with decreasing porosity of the initial gels, whereas the PL decay dynamics tends to deviate from a pure exponential trend as the porosity of the initial gels becomes higher. These results indicate that the formation, stabilization, and radiative recombination process of the emission centers that are created during annealing are influenced by the microscopic morphology of the gels. These experimental results are interpreted in terms of the formation mechanism of the visible emission center in silica-based nanostructure materials proposed recently (Uchino, T.; Kurumoto, N.; Sagawa, N.

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Optical Determinations of OH in Fused Silica

Cited by 55 publications

References 1 publication

An Experimental Study of Water and Carbon Dioxide Solubilities in Mid-Ocean Ridge Basaltic Liquids. Part I: Calibration and Solubility Models

An Experimental Study of Water and Carbon Dioxide Solubilities in Mid-Ocean Ridge Basaltic Liquids. Part I: Calibration and Solubility Models

Quantification of Water and Silanol Species on Various Silicas by Coupling IR Spectroscopy and in-Situ Thermogravimetry

Effect of Microscopic Structure and Porosity on the Photoluminescence Properties of Silica Gels

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