Spectroscopy of diatomic ZrF and ZrCl: 760 ? 555 nm

The optical spectrum of diatomic ZrF has been investigated, with transitions recorded in the range from 14 700 to 18 000 cm?1. Many bands have been observed, several of which can be grouped into three band systems. Rotationally resolved investigations are hampered by perturbations that are rampant among the excited states, but three unperturbed bands have revealed that the ground state of ZrF has ?" = 3/2, with a bond length of r"e = 1.854(1) ?. Hot bands originating from v" = 1 provide the ground state vibrational interval, ?G"1/2 = 691.45(2) cm?1 for 90Zr19F. Based on comparisons to ZrCl and ligand-field considerations, the ZrF ground state is assigned as a 2?3/2 level deriving from the 3?2 1?1 configuration, in agreement with a previous study. In addition to the measurements on ZrF, vibronically resolved spectra of ZrCl have been recorded over the 13 000 to 18 000 cm?1 range, and four band systems have been identified.