Rotational analysis and assignment of the 630 nm band system of FeH to the e6Π-c 6Σ+ transition

An investigation of the electronic spectrum of FeH at similar to 630 nm using dispersed and undispersed laser induced fluorescence techniques is reported. Eighty lines have been assigned to the (0, 0) vibrational band of the e (6) Pi-c 6 Sigma(+) transition. The transitions can be arranged in three subbands with all six spin components of the c (6) Sigma(+) state accessed. This has allowed the c (6) Sigma(+) state to be fully characterized and provides parity assignments of individual rotational levels for the first time, The energy levels of the c (6) Sigma(+) state conform approximately to a Hund's case (a') coupling scheme with significant Omega-type doubling (1-10 cm(-1)). An attempt has been made to simulate the levels using an effective Hamiltonian, Although the simulation failed to reproduce the results to within experimental uncertainty (similar to 0.007 cm(-1)), the residuals are sufficiently small to confirm the correctness of the assignments. (C) 1998 American Institute of Physics.