Rotationally resolved spectroscopy of Pt2

High-resolution laser-induced fluorescence spectroscopy has been used to investigate the 18 163 cm(-1) band of Pt-2 in a supersonically cooled molecular beam. Rotational constants of the ground and excited states were extracted from the rotationally resolved spectrum and determined to be B-0" = 0.031754(12) cm(-1) and B-0' = 0.028 672(11) cm(-1), respectively. These values correspond to ground- and excited-state bond lengths of r(0)" = 2.33297(44) Angstrom and r(0)' = 2.455 t6(47) Angstrom, respectively. Nuclear spin statistics that are observed in the spectrum demonstrate that the around state is of either 0(g)(+) or 0(u)(-) symmetry. Of these, 0(g)(+) is by far the more probable. Comparisons with Au-2 are made, suggesting that it may be appropriate to consider Pt-2 as having a double bond. (C) 2002 American Institute of Physics.