The electric dipole moments in the ground states of gold oxide, AuO, and gold sulfide, AuS.

The B2Σ- - X2Π3/2(0,0) bands of a cold molecular beam sample of gold monoxide, AuO, and gold monosulfide, AuS, have been recorded at high resolution both field free and in the presence of a static electric field. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, μ→el, of 2.94±0.06 D and 2.22±0.05 D for the X2Π3/2(v = 0) states of AuO and AuS, respectively. A molecular orbital correlation diagram is used to rationalize the trend in ground state μ→el values for AuX (X = F, Cl, O, and S) molecules. The experimentally determined μ→el are compared to those computed at the coupled-cluster singles and doubles (CCSD) level augmented with a perturbative inclusion of triple excitations (CCSD(T)) level of theory.