The chemiluminescent flame spectrum of SiO

The band systems of the SiO molecule have been excited in a flame produced by the chemiluminescence of SiCl ₄ vapor reacting with oxygen atoms in the presence of an argon atmosphere. A general survey has been made of the emission spectrum of this flame and the various band systems lying in the region 2300-4600 Å have been identified. Many new bands have been observed and have been assigned to the SiO molecule. The emission bands tentatively attributed to a new ¹Σ ^-- ¹Σ ^- transition of neutral SiO [H. Bredohl, R. Cornet, I. Dubois, and F. Remy, Can. J. Phys.51, 2322 (1973)] and reassigned by R. F. Barrow and T. J. Stone [ J. Phys. B.8, L13 (1975)] to belong to the known E¹Σ ⁺- X¹Σ ⁺ system of SiO have been extended in the present source. They are shown to confirm the Barrow and Stone assignments. A few bandheads corresponding to the isotopic species ²⁹SiO and ³⁰SiO have been observed for A¹Π- X¹Σ ⁺ system. In addition, several strong unidentified bands have been reported.