Photodissociation spectra of transition metal sulfides: spin–orbit structure in charge transfer bands of FeS+ and NiS+

Photofragment spectra of FeS+ and NiS+ are reported. Analysis of the FeS+ spectrum reveals it to arise from a 6Π←6Σ charge-transfer transition, and gives the vibrational frequency, ωe′=295 cm−1, and spin–orbit constant, |A|=125 cm−1, in the 6Π state. The onset of the NiS+ spectrum appears to occur in the middle of a vibrational progression, thus giving a precise measurement of the Ni+–S bond strength, D0(Ni+–S)=238±4 kJ mol−1. Analysis of the spectrum for vibrational and spin–orbit structure leads to a tentative assignment of a 4Δ ground state and suggests the spectrum is composed of overlapping transitions to two near-degenerate excited electronic states, most likely a 4Π and 4Φ pair.