High resolution IR spectroscopy of low temperature matrices. The structure of fundamental absorption bands of SiH$_{4}$ in nitrogen and argon matrices

The features of high resolution IR spectra of the SiH$_{4}$ molecule in N$_2$ and Ar low-temperature matrices at 6.6–20 K were analyzed depending on experimental conditions. It was found, that in the nitrogen matrix in region of stretching vibration of $^{28}$SiH$_{4}$ three narrow bands are observed, in the region of bending vibration ($\nu_4$) two bands are observed instead of one, which is explained by a change in the symmetry of the molecule from $T_d$ in the gas phase to $C_{3v}$ in solid nitrogen. In the argon matrix spectra change even more, where, in addition to narrow bands, the broad enough components are also recorded. The calculations of the SiH$_{4}$ spectrum in the Ar matrix were performed based on the QM/MM approach, which confirm the reality of the change in the symmetry of the molecule as a result of its interaction with the matrix environment.