Knowledge Bank

The infrared spectrum of dideuteroacetylene, $C2D2$, is considerably complicated by the presence of numerous hot'' bands originating from the two low-lying levels, $0001^{1}0^{0} (\Pi_{g})$ and $0000^{0}1^{1} (\Pi_{u})$. Rotational analysis of these hot'' bands brought to light strong interactions among states with $(v4+v5)⩾2$: for example, in the group of interacting states $0002000,0002200,0000020$, and $0000022$, the separation between $0002000$ and $0002200$ is only $\sim 0.35cm-1$ resulting in a very strong perturbation of the rotational levels of the $\Delta g(c)$ and $\Sigma g+$ states (the $\Delta g(d)$ state shows regular behaviour). Transitions involving $\Sigma u-$ and $\Sigma g-$ states have also been identified for the first time in a vibrational-rotational spectrum.

Author Institution: Division of Pure Physics, National Research Council of Canada; Department of Physics, The Ohio State University