A new 2Π i- X2Π r band system of NS

Vibrational and rotational analysis of four bands of NS lying in the region 2550-2665 Å is reported. They form a new band system involving a ²Π _i- ²Π _r transition and arise from a common initial vibrational level v' = 0 to v″ = 4 and 5 levels of the ground state. The assignment of v', v″ quantum numbers is supported by isotope shift data from N ³⁴S and ∆ ₂F ( J) values of the v = 4 and 5 levels of the X² Π state.