Dispersed excitation spectroscopy of some weak transitions of NiF

Dispersed excitation spectroscopy, recorded through a spectrometer used as a narrowband filter, made it possible to obtain the rotational analysis of weak blended transitions of NiF. Five electronic transitions, involving a common upper state and five lower states, have been observed in the visible region. One of these transitions (17 529.5 cm(-1)) has been rotationally analyzed. Both the energy splittings between the five new low-lying states and the value of the rotational constant of the lower state of the transition analyzed (B = 0.38511 cm(-1)) are evidence that these states are not the already known five lower doublet states. Another transition (18 348 cm(-1)) involving the ground (2) Pi(3/2) state of NiF has been partially analyzed. The upper state (B' = 0.3702 cm(-1)) is also linked to the lower (2) Sigma states but not to the components of the (2) Delta state, ruling out a (2) Pi(1/2) assignment for this upper state. All these results suggest that the new observed states could be components of quartet states. (C) 1997 Academic Press.