The infrared spectrum of silicon difluoride

Millimeter and submillimeter-wave spectroscopy of silicon difluoride

“…In addition, equilibrium values of the quartic distortion constants of 28 SiF 2 could be calculated, and the Coriolis [14]. b Derived from UV data.…”

“…resonance between the v 1 = 1 and v 3 = 1 states has been reanalyzed including a large number of ro-vibrational interstate transitions. The large and considerably improved set of rotational data has been employed to refine by a least-squares procedure the cubic force field previously published [3], using also more precise vibrational wavenumbers [14,15], and reliable constraints deriving from a theoretically computed force field [16]. The obtained force field provides the set of potential constants which allow to reproduce with the highest accuracy the whole body of rotational and vibrational data presently available for the electronic ground state of silicon difluoride.…”

“…Afterwards, more precise values of the m 1 and m 3 band origins were obtained by medium resolution FTIR spectroscopy [14], and a better determination of m 2 resulted from the study of the T 1 ‹ S 0 band system of SiF 2 [15]. In addition, Pak and Woods [16] calculated the quartic force field of silicon difluoride at the CCSD(T) level of theory using the cc-pVQZ basis set.…”

“…The present work now provides a large set of very accurate rotational parameters which can be related to the potential constants. The availability of new experimental and theoretical data makes desirable to perform a refinement of the anharmonic force field of silicon difluoride by a least-squares procedure which, starting from the CCSD(T)/cc-pVQZ values of [16], optimizes the quadratic and cubic force constants to reproduce the large variety of spectroscopic parameters presently available for this molecule, which includes the three fundamental vibrational wavenumbers of 28 SiF 2 [14,15], quartic and sextic centrifugal distortion constants, inertial defects for ground and excited vibrational states, Coriolis coupling coefficients, and a vibration-rotation interaction constants. Since [15] does not provide directly the value of the m 2 band origin, it has been calculated through a reanalysis of the published data, which yields m 2 = 342.0 ± 2.3 cm À1 .…”

Coupled cluster prediction of vibrational band intensities for SiF2 and PF2+

“…We have shown earlier in the cases of CF 2 and ozone 4 that ab initio methods can provide S values to the accuracy required for reliable concentration measurements. Fourier transform infrared ͑FTIR͒ spectroscopy has been applied to the stretching fundamentals of SiF 2 in the gas phase by Caldow et al, 5 yielding the band origins and the relative ͑but not the absolute͒ intensities of the two bands. Much less is known about PF 2 ϩ , but mass spectroscopic study in our laboratory 6 has shown it to be abundant in PF 3 containing glow discharges.…”