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T. H. LE AND W. R. M. GRAHAM, Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129.
This paper follows preliminary results on the SiC5 molecule presented earlier. An absorption at 936.9 \pm 0.2 cm-1 has been identified as the
4(
) Si-C stretching fundamental of linear SiC5. Its assignment has been confirmed by the close agreement between DFT predicted and observed 13C isotopic shifts. DFT-B3LYP calculations predict that two other C-C fundamentals,
1(
) and
2(
) of SiC5 should have intensities 10 to 15 times stronger than
4(
), but would appear in the C-C stretching frequency regions.
Refinements of the Si-C laser ablation techniques have helped to reveal the isotopic 13C shifts for two additional absorptions at 2045.0 and 1992.9 cm-1. Comparison of their observed isotopic shifts with the predictions of DFT calculations at the MPW1PW91/6-311+G(3fd) level have led to their assignment to the
1(
) and
2(
) fundamentals of SiC5.