The D and D′ states of the PO molecule

Abstract

A rotational analysis of the 0–0, 0–1, and 0–2 bands of the D–B and D′–B systems of PO in the region 5500–6900 Å has been carried out from a spectrum obtained at a resolution higher than that of previous workers (Couet and Guenebaut 1966; Couet et al. 1967). The mutual perturbation between D2Πr and D′2Πr has been confirmed from the rotational analysis of the 0–0 and 0–1 bands of the D–A and D′–X systems in the region 2000–2200 Å. The analysis of the D′–X bands has shown that the previously reported E′ state lying between the D and D′ states is actually part of the D′ state. The constants of the D2Πr, D′ 2Πr, B2Σ+, and X2Π states are evaluated and compared with the constants of earlier workers to remove the inconsistency existing in their values for the B and X states.The isotopic bands corresponding to P18O of the D–B and D′–B systems are obtained, thus showing that the D′ state has an anomalous isotopic shift and that the observed levels of the D and D′ states have the vibrational quantum number ν =.