Knowledge Bank

The five-atomic linear molecules carbon suboxide, $O=C=C=C=O$, tricarbon oxide sulfide, $O=C=C=C=S$, and carbon subsulfide, $S=C=C=C=S$, are of considerable interest for both spectroscopists and $astronomers1$. Carbon suboxide belongs to the exotic group of quasilinear $molecules1$, while the microwave experiments of $C3OS$ revealed beyond doubt the spectrum of a linear $molecule1$. In the case of $C3OS$ a new high yield $synthesis2$ allows high-resolution study in the infrared region. In order to provide precision data for the assignment of the forthcoming high-resolution infrared spectra we have measured the milimeter wave spectrum of $C3OS$ for molecules in various excited vibrational states. The results of these studies will be discussed within the framework of earlier studies of O=C=C=C=S and recent work on $S=C=C=C=S3$.