High resolution study of strongly interacting ν3(F2)/ν1(A1) bands of MSiH4 (M=28,29,30)

- High resolution analysis of the v1/v3 bands of 28SiH4, 29SiH4, and 30SiH4.
- Resonance interactions in spherical top molecules.
- Determination of spectroscopic parameters.
- Analysis of line intensities and half-widths.

The high resolution (0.0021-0.0025  cm−1) infrared spectra of SiH4 in natural abundance (92.23 % of 28SiH4, 4.68 % of 29SiH4, and 3.09 % of 30SiH4) were measured in the 2000-2350  cm−1 region with a Bruker IFS 120HR Fourier transform spectrometer. The 2584 transitions with Jmax. = 27 were assigned to the ν3 and ν1 bands of 28SiH4. Rotational, centrifugal distortion, tetrahedral splitting, and resonance interaction parameters for the (0010) and (1000) vibrational states were determined from the weighted fit of experimental line positions. The obtained set of parameters reproduces the initial experimental data with an accuracy close to experimental uncertainties. The results of analogous analyses of the 29SiH4 and 30SiH4 isotopologues (the numbers of assigned transitions are 811 and 986 both with Jmax. = 23) were made with the use of the isotopic substitution theory relations. A further analysis of 379 experimental ro-vibrational lines of the ν3 and ν1 bands of 28SiH4 was performed using the Hartmann-Tran profile to simulate the measured line shape and to determine experimental line intensities. The 4 effective dipole moment parameters were obtained on that basis from the weighted fit, which reproduce the initial experimental intensities of the 379 initial lines (both strong and weak) with the drms=7.6% (the 148 strongest lines are reproduced with the drms=5.0%). Analogous analyses were made for the two other isotopic species, 29SiH4, and 30SiH4. A detailed line list of transitions in the region of 2000-2350  cm−1 is presented. The half-widths of 100 ro-vibrational lines (Jup.max.=17) are analyzed from the multi-spectrum fit, and self-pressure broadening coefficients are determined.