Knowledge Bank

High resolution laser excitation spectra have been obtained for several transitions involving three of the lowest lying states of SmO. Very careful wavelength selected detection enabled us to eliminate unwanted overlapping transitions and to obtain separate spectra for the individual e.f parity components of an $\Omega =1-1$ transition. The rotational structure has been assigned for six isotopic species and the molecular constants computed using a simultaneous least squares fit to all the transitions. Some parity and isotope dependent perturbations were observed in the [16.9]1 state. The results of the analysis will be presented and the rotational constants, $\Omega$-doubling, isotope effects and the interpretation of perturbations will all be discussed.