Abstract

The<i> in situ</i> Fourier transform infrared (FT-IR) spectrum of gasphase SiO produced in silicon oxynitride fiber growth has been quantitatively analyzed. Both absorption and emission FT-IR spectra at a spectral resolution of 0.5 cm^-1 were produced from the reaction zone at 1450 °C. The fundamental and hot bands were observed with vibrational levels up to<i> v</i> = 7. For the purposes of quantitative analysis the individual vibration–rotation integrated line strengths for the three main isotopes,²⁸SiO,²⁹SiO, and³⁰SiO, were calculated based on<i> ab initio</i> quantum chemical calculations of the electric dipole moment function and the transition moment. Vibrational anharmonicity and Hermann–Wallis correction factors were also incorporated. From the line strengths at specific temperatures and the known Dunham coefficients, the absorbance spectrum was simulated with best fits giving the averaged SiO concentration in the 400 mm reaction zone of 1.0 × 10¹⁷ molecules/cm³. Such quantitative measurements demonstrate the power of<i> in situ</i> infrared (IR) spectroscopy combined with quantum chemical calculations. The rapid determination of synthetic calibration datasets for chemometric analysis can thus lead to correlation of gas-phase species concentrations with fiber growth properties and subsequently to real-time process control.

Ion beam sputtered (SiO₂)x(Si₃N₄)₁₋x antireflection coatings on laser facets produced using O₂–N₂ discharges

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Quantitative measurements by Fourier-transform infrared spectroscopy of toxic gas production during inhibition of JP-8 fires by CF₃Br and C₃F₇H

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Quantitative absorption spectroscopy of residual water vapor in high-purity gases: pressure broadening of the 1.39253-μm H₂O transition by N₂, HCl, HBr, Cl₂, and O₂

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Fourier-transform spectra of the A²Σ⁺–X²Π Δv = 0 bands of OH and OD

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