Identification of New Hot Bands in the Blue and Green Band Systems of FeH

A particularly rich region of the electronic spectrum of FeH from 525 to 545 nm was investigated using the techniques of dispersed and undispersed laser-induced fluorescence. Analysis has led to the discovery that several different electronic transitions are embedded in this region; the (0, 0) and (1, 1) bands of the e(6)Pi-a(6)Delta (green) system, the (0, 2) band of the g(6)Phi-X(4)Delta (intercombination) system, the (0, 1) band of the g(6)Phi-a(6)Delta (blue) system, and the (0, 0) band of the g(6)Phi-b(6)Pi system. Seventy-five lines were assigned in the (0, 1) band of the g(6)Phi-a(6)Delta transition. These, with the assignment of an additional 14 lines in the 583 nm region to the (0, 1) band of the e(6)Pi-a(6)Delta transition, led to the extension of the known term values to higher J values for the Omega = 9/2, 7/2, and 5/2 spin components of the v = 1 level of the a(6)Delta state and the novel characterization of the a(6)Delta(3/2) (v = 1) and g(6)Phi(5/2) (v = 0) components. A further 73 lines were assigned to the first four subbands of the (1, 1) band of the e(6)Pi-a(6)Delta transition and term values for the lowest four spin components of the v = 1 level of the e(6)Pi state were determined. This provides the first experimental measurement of a vibrational interval in one of the higher lying electronic states of FeH. The interval does not appear to vary strongly between the spin components (DeltaG(1/2) = 1717, 1713, 1710 cm(-1) for Omega = 7/2, 5/2, 3/2, respectively). Remarkably few of the hot-band transitions assigned in this work could be identified in the complex, high-temperature spectrum of FeH recorded by P. McCormack and S. O'Connor [Astron. Astrophys. Suppl. 26, 373-380 (1976)]. Copyright 1999 Academic Press.