Transition metal sulfide studies: the pure rotational spectrum of the CuS radical (X2Πi)

The pure rotational spectrum of CuS in its X2Πi ground state has been recorded using direct absorption techniques in the range 140–540 GHz. This radical was produced by the reaction of copper vapour with CS2. Both the v=0 and v=1 states of 63CuS were observed, as well as the 65CuS (v=0) isotopomer. 25, 13, and 8 rotational transitions were recorded for these three species, respectively. Both the Ω=1/2 and Ω=3/2 spin–orbit ladders were observed. Accurate rotational, spin–orbit, and lambda-doubling constants were subsequently determined for these molecules. These data suggest that 3d-sulfides have subtle bonding differences relative to the corresponding 3d-oxides.