A theoretical investigation of the astrophysically important molecules C3O and HC3O+

Abstract

Large-scale CEPA calculations have been carried out for the astrophysically important molecules C3O and HC3O+. C3O has a linear equilibrium geometry with short terminal CC and CO bond lengths of 1.273 and 1.149 Å and a central CC equilibrium bond length of 1.300 Å. Upon protonation the terminal CC and CO bond lengths are shortened by 0.061 and 0.026 Å, respectively, while the central CC bond length experiences an elongation by 0.052 Å. C3O has a noticeably large equilibrium dipole moment of 2.535 D with the positive end at the oxygen site. The IR intensity of the ν1 band at 2229 cm−1 is extremely large (72 756 cm2 mol−1). Although the intensity of the corresponding ν2 band of HC3O+ at 2318 cm−1 is only about one half as large this band appears to be most promising for future IR diode laser investigation. The proton affinity of C3O at 298 K is 885±5 kJ mol−1.