Knowledge Bank

The rotational spectrum of $C3H$ observed in two astronomical sources and in the laboratory showed that it has a linear structure with a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Pi$ ground state. Ab initio calculations by $Green1$ support this model. In a previous 1R $study,2$ bands at 1834 and $1826cm-1$ obtained by the vacuum uv photolysis of methylacetylene and allene were assigned to an antisymmetric C-C stretch mode of $C3H$, and the same mode of $C3D$ was also reported. In the present FTIR study using the photolysis of methylacetylene and its deuterated counterparts, vibrational frequencies in addition to those reported earlier by Jacox and Milligan, have been observed. The analysis for $C3H$ and $C3D$ will be reported.