Vibrational spectra of tetra-atomic silicon–carbon clusters. II. Si2C2 in Ar at 10 K

Abstract

Fourier transform infrared measurements on the spectra of the products of the vaporization of silicon/carbon mixtures trapped in solid argon in concert with ab initio calculations using second order many body perturbation theory have resulted in the identification for the first time of two vibrational fundamentals, 3 (b 1u )ϭ982.9 and 4 (b 2u )ϭ382.2 cm Ϫ1 , of the rhombic ground state structure of Si 2 C 2 . The observed frequencies, intensities, and isotopic shifts are in good agreement with the ab initio predictions. Tentative assignments are also made for fundamentals of the linear ͑SiCCSi͒ and distorted trapezoidal isomers. The relative energies of the three isomers have been estimated at various ab initio levels.

Study of absorption spectra and (hyper)polarizabilities of SiCn and SinC (n=2–6) clusters using density functional response approach

“…Experimental studies are mainly carried out by optical absorption spectroscopy, 4-13 mass spectrometry ͑MS͒, 14,15 and photoelectron spectroscopy. 16,17 From Fourier-transform infrared ͑FTIR͒ studies, a series of small SiC clusters with the following geometries have been identified: triangular SiC 2 , 7,11 rhomboidal Si 3 C, 9 rhombic Si 2 C 2 , 5 linear SiC 4 , 13 linear Si 2 C 3 , 8 pentagonal Si 3 C 2 , 10 and linear Si 2 C 4 . 6 The visible absorption spectrum 11,12 of SiC 2 shows a strong absorption peak at ϳ490 nm.…”

High-resolution laser spectroscopy of the linear SiC2Si molecule and its astrophysical implications

“…Based on the vibrational mode symmetries and the theoretically predicted vibrational frequencies (Rintelman & Gordon 2001;Presilla-Márquez et al 1995;Fitzgerald & Bartlett 1990;Lammertsma & Guner 1988), bands B (5120 Å) and C (5071 Å) are tentatively assigned to the 5 2 0 and 2 1 0 vibronic transitions, respectively. This results in the 2ν 5 (overtone of the symmetric bending mode) and 1ν 2 (symmetric Si-C stretching mode) vibrational level energies in the upperC 3 Σ − u state to be 129.3 and 347.5 cm −1 , respectively, both of which are significantly smaller than the theoretically predicted ground-state values (256 and 460 cm −1 , respectively, in Rintelman & Gordon 2001).…”

“…Quantum chemistry calculations have shown that two isomers of Si 2 C 2 , the rhombic D 2h structure (D 2h , r-Si 2 C 2 ) and the linear SiC 2 Si (D ∞h , l-Si 2 C 2 ) structure (see Fig. 1), are nearly isoenergetic (Rintelman & Gordon 2001;Presilla-Márquez et al 1995;Fitzgerald & Bartlett 1990;Lammertsma & Guner 1988). Density functional theory calculations predicted the r-Si 2 C 2 structure to be the most stable form, while the l-Si 2 C 2 struc-ture lies only ∼0.01 eV higher.…”

Fourier transform infrared identification of the ν5(σ u) fundamental of SiC5Si

“…This criterion was established empirically via previous Si m C n assignments by this lab. 4,7,8,[19][20][21][22][23][24][25] …”

“…7 With the addition of a third carbon atom, MBPT(2) calculations predict a linear SiC 3 Si geometry is lowest in a) Author to whom correspondence should be addressed. Electronic mail:…”