Identification of optical lines in a molecular band by rf labelling; application to hfs in ScO,X 2 ?+,v=1

Abstract

It is shown how individual rotational lines in a dense molecular band may be rapidly and positively identified by an rf-labelling method. The molecular-beam, laser-rf, double-resonance scheme allows precise measurement of lower-state hfs and spin-rotation splittings. Since correct assignment of all quantum numbers to such observations is a prerequisite for a satisfactory self-consistent least-squares fit of the Hamiltonian to the data, positive line identifications result. As knowledge of the interaction strengths is progressively refined, it rapidly becomes possible to predict all lower-state splittings, and this knowledge in turn leads to identification of the remaining rotational lines. The method is applied to identification of rotational lines in theA↔X (v′=1↔v″=1) transition in ScO. Although a major perturbation of theA2∏ state energies (resulting in breaking the monotonic distribution of rotational lines in the band) was unexpectedly found, the labelling method led to quick and positive identification of the lines. Spin-rotation and hfs results are given for theX2Σ+ (v=1) manifold of ScO.