New assignments in the green and red band systems of the FeH radical

The electronic spectrum of Fell in the regions of the 532 nm (green) and 630 nm (red) systems has been investigated using the techniques of dispersed and undispersed laser induced fluorescence. Sixteen lines have been assigned in the Omega = 1/2 <-- Omega = -1/2 subband of the e(6)II-c(6)Sigma(+) transition and term values determined for the previously uncharacterized e(6)II(1/2) spin-orbit component. A further fourteen lines were assigned to the connected Omega = 1/2 <-- Omega = 3/2 subband of the e(6)II-a(6)Delta transition and term values for the hitherto uncharacterized a(6)Delta(3/2) component were determined. A study of the high-temperature spectrum of FeH, recorded previously by McCormack and O'Connor (1), enabled the branches of the Omega = 7/2 <-- Omega = 9/2 subband of the e(6)II-a(6)Delta transition to be extended to higher J values. These predictions were confirmed by laser induced fluorescence (LIF) experiments and led to the assignment of 13 additional lines in this subband. The term values for the e(6)II(7/2) and a(6)Delta(9/2) spin-orbit components were thus extended to higher J values. (C) 1998 Academic Press.