Identification of new low-lying electronic states of the FeF radical

Dispersed fluorescence studies on the (6)Pi-X(6)Delta and (6)Phi-X(6)Delta systems of the FeF radical have resulted in the observation of vibrational progressions for transitions to the X(6)Delta state as well as at least two previously unobserved electronic states about 5000 cm(-1) above the ground state. The states are assigned as the A(6)Pi and B(6)Sigma(+) electronic states. The spin components of both electronic states were found to be heavily perturbed resulting in uneven splittings between them. A third, weak series was also observed but could not be assigned. The (0,0) band of the (6)Pi(7/2)-B(6)Sigma(5/2)(+) transition at 398 run was observed in absorption by laser induced fluorescence and its rotational structure was assigned. The spectra obtained were weak because of a poor population of the B(6)Sigma(+) state by the reaction used to form FeF. The levels were found to be markedly perturbed at high J values. Attempts were made to fit the data on the (6)Pi(7/2)-B(6)Sigma(5/2)(+) system to an effective Hamiltonian, but the presence of perturbations meant that the system is not well described by such a model. (C) 2002 Elsevier Science (USA).