The VUV Absorption Spectrum of SiO: Three New Ionization Limits

Abstract The absorption spectrum of SiO has been observed down to 250 A. Besides the Rydberg series reported by M. A. Baig and J. P. Connerade (1979, J. Phys. B: At. Mol. Phys. 12, 2309–2318), three new groups of Rydberg series have been observed converging at 18.59, 22.64, and 37.07 eV. These new limits are compared to theoretical calculations (K. L. Cai and J. P. Francois, 1999, J. Mol. Spectrosc. 197, 12–18) and to the isovalent molecule CO.