The electronic spectrum of the fluoroborane free radical. II. Analysis of laser-induced fluorescence and single vibronic level emission spectra The electronic spectrum of the fluoroborane free radical. I. Theoretical calculation of the vibronic energy levels of the ground and first excited electronic states Rotational analysis and assignment of the green band system of FeH to the e6Π-a6Δ transitionThe electronic spectrum of the FeH radical at near ambient ͑ϳ450 K͒ temperature has been re-investigated at high resolution. More than 150 lines have been assigned by the use of LIF and dispersed LIF techniques. Dispersed fluorescence experiments in the green region have shown surprisingly strong ⌬⍀ϭ0, ϩ1, ϩ2... transitions in the e 6 ⌸ -a 6 ⌬ system, for which the case ͑a͒ selection rule is ⌬⍀ϭϪ1. The analysis of ⌬⍀ϭ0 and Ϫ1 sub-bands in this system has given term values in the previously unseen ⍀ϭ1/2 and Ϫ1/2 components of a 6 ⌬ (vϭ0), e 6 ⌸ Ϫ1/2 (vϭ0) and a 6 ⌬ 1/2 (vϭ1). The a 6 ⌬ state is now experimentally confirmed as a state of sextet nature and is only the second sextet state of FeH to be seen in all spin-orbit components ͑the other is c 6 ⌺ ϩ ͒. The a 6 ⌬ state is not well-described by a single state effective Hamiltonian; the best fit to this model gives a standard deviation of around 125 times the experimental error. In addition, term values have been determined for a set of levels whose term value origin lies at 3175 cm Ϫ1 above the ground state. These have been tentatively assigned to the vϭ0 level of the C 4 ⌽ 9/2 component and are hypothesised to be the cause of the known perturbation to the a 6 ⌬ 9/2 (vϭ1) level.