Line intensity measurements and analysis in the ν₃ band of ruthenium tetroxide

Highlights: • High resolution Fourier transform spectroscopy of pure ¹⁰²RuO₄ from 895 to 945 cm^–1. • Six experiments conducted at the AILES beamline of SOLEIL using synchrotron radiation. • 266 line intensities measured for the first time in the ν₃ band. • 198 line intensities fitted using a global tensorial model (RMS deviation of 8.0%). • HITRAN-formatted list of 3373 lines for the ν₃ band of ¹⁰²Ru¹⁶O₄. - Abstract: Ruthenium tetroxide (RuO₄) is a heavy tetrahedral molecule characterized by an unusual volatility near ambient temperature. Because of its chemical toxicity and the radiological impact of its ¹⁰³Ru and ¹⁰⁶Ru isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. The present contribution is the first investigation dealing with high-resolution line-by-line intensity measurements for the strong fundamental band observed near 10 μm, associated with the excitation of the infrared active stretching mode ν₃. It relies on new, high resolution FTIR spectra recorded at room temperature, using a specially constructed cell and an isotopically pure sample of ¹⁰²Ru¹⁶O₄. Relying on an effective Hamiltonian and associated effective dipole moment [S Reymond–Laruinaz et al, J Mol Spectrosc 2015;315:46–54], the measured line intensities were assigned and dipole moment parameters determined. A HITRAN-formatted frequency and intensity line list was generated.