A matrix isolation and theoretical study of SiF4 dimers spectra

The absorption spectra of (SiF4)2 dimers were studied in argon, xenon and nitrogen matrices. The dimer νX,Y, νZ bands due to resonance dipole-dipole interaction between two SiF4 subunits were identified. The ab initio calculations of the structure, energies and vibrational frequencies for the different conformations of (SiF4)2 dimer were performed using the second-order Møller-Plesset perturbation theory. The model with the point dipole moments located on each of Si-F bonds has been developed. This model allows to calculate the dimers spectra at various orientation of SiF4 molecules. On transition from the gas to low temperature matrix the symmetry of (SiF4)2 dimer changes from C2h to D2d, and RSi-Si distance decreases by 0.3 Å.