High-resolution spectroscopy and analysis of the v(3), v(4) and 2v(4) bands of SiF4 in natural isotopic abundance

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 v(3) and v(4) fundamental bands, for the three isotopologues in natural abundance: (SiF4)-Si-28 (92.23 %), (SiF4)-Si-29 (4.67 %) and (SiF4)-Si-30 (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 2v(4) band of (SiF4)-Si-28 could also be analyzed in detail. A first fit of the dipole moment derivative for the v(3) band for( 28)SiF(4) 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 v(3) band of SiF4, has been set up. (C) 2020 Elsevier Ltd. All rights reserved.