High-resolution spectroscopy and analysis of the ν3, ν4 and 2ν4 bands of SiF4 in natural isotopic abundance
Résumé
Silicon tetrafluoride (SiF4) is a trace component of volcanic gases. However, a better knowledge of spectroscopic parameters is needed for this molecule in order to derive accurate concentrations. This motivated FTIR measurements with high-spectral resolution (0.001 cm-1) and an extensive study of its infrared absorption bands, including the fundamentals and overtone and combinations. We present here a detailed analysis and modeling of the strongly absorbing ν3and ν4 fundamental bands, for the three isotopologues in natural abundance: 28SiF4 (92.23 %), 29SiF4 (4.67 %) and 30SiF4 (3.10 %). It includes a global fit with consistent parameter sets for the ground and excited states. In particular, all existing rotational line data have been included. The 2ν4 band of 28SiF4 could also be analyzed in detail. A first fit of the dipole moment derivative for the ν3 band for 28SiF4 has been performed, along with two independent estimates of the integrated band intensity; the results are consistent with literature values, around 690 km/mol. The isotopic dependence of band centers and Coriolis parameters has also been studied. TFSiCaSDa, a new database of cross sections and calculated lines for the ν3 band of SiF4, has been set up.
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