AN electronic system of the molecule NbO+ has been analysed and has been shown to be an unparalleled example of the coupling of electron and nuclear spins described as case aβ; that is, one in which the electronic momenta are tightly coupled to the internuclear axis while the nuclear spin is quantized in the laboratory frame1,2 (rather than in the internal internuclear axis system). The system has been observed in emission in the red region of the optical spectrum using a resolving power which is theoretically about 500,000—that is, energy differences of about 0.035 cm-1 can be observed. It consists of only a 0,0 sequence and has been analysed as 3Φ→3Δ. The three 0,0 sub-bands have been observed as shown in Table 1.