Microwave observation of the "recently found" polar OCS dimer

Recently Afshari et al. reported on the detection of a new infrared band which was assigned to the "long-anticipated polar isomer of the OCS dimer" [J. Chem. Phys. 126, 071102 (2007)]. The authors report here the microwave confirmation of their results. The lowest energy, nonpolar isomer of (OCS)2 has long been known from IR spectroscopy, while the polar form has only been deduced from qualitative beam refocusing experiments. The higher energy, polar isomer of (OCS)2 has been produced by high pressure expansion of dilute OCS in helium. A surprisingly strong microwave spectrum of Cs (OCS)2 has been observed and assigned.