New results on the <i>D</i>²Π and B′²Π states of the PO molecule

Abstract

A rotational analysis of the D–X and D′–X band systems of PO in the region 1900–2100 Å has been reinvestigated from an absorption spectrum taken at high resolution. A new ν = 1 vibrational level of the D 2 Π state of PO interacting with a new vibrational level of the D′ 2 Π state has been studied in detail. Two other new vibrational levels, ν = 2 and 3, of D 2 Π have been recorded and studied in detail. A rigorous deperturbation of the D and D′ levels has been carried out. It has been shown that D′ 2 Π and B′ 2 Π are one and the same state of the PO molecule. A new band overlapped by the D′–X, 26–0 band has been attributed to the B 2 Σ + –X 2 Π transition.