The fluorescence lifetimes of the gerade states of HD near the second dissociation limit

An extreme ultraviolet-visible two step excitation scheme has been employed to populate rovibronic levels of the EF¹Σg⁺, GK¹Σg⁺, H¹Σg⁺, I¹Πg, and J¹Δg states of HD near the second dissociation limit. Term values and fluorescence lifetimes are determined for the newly identified 17 rovibronic levels. In addition to the overall g-u symmetry breakdown in the wide energy range covering the excitation energies of the EF¹Σg⁺ and B¹Σu⁺ states, a strong accidental g-u mixing is observed between GK¹Σg⁺(v = 9, J = 1) and B′¹Σu⁺(v = 7, J = 1).