The Sep Spectrum of Acetylene: Symmetry Properties and Isomerization

Quantum Dynamics of Vinylidene Photodetachment on an Accurate Global Acetylene-Vinylidene Potential Energy Surface

“…Vinylidene (H 2 CC), a high-energy isomer of acetylene (HCCH), is known to play an important role in many reactive environments, including combustion . As a prototype for the 1,2-hydrogen shift, the isomerization dynamics between the two isomers has attracted much attention in the past. − Experimentally, the large amplitude bending vibrations of acetylene along the isomerization pathway have been probed spectroscopically by Field and co-workers. − Highly excited bending overtones on the ground electronic state have been identified via stimulated emission and fluorescence techniques to energies just below the isomerization barrier, although direct spectroscopic detection of vinylidene has so far been unsuccessful . These spectroscopic studies have revealed interesting patterns in the form of a normal-to-local transition for the acetylene bending vibrations. , The isomerization dynamics has also been investigated experimentally by Lineberger and co-workers using negative ion photodetachment. , The ejection of an electron from the stable vinylidene anion places the system on the neutral state near the vinylidene isomer, and the ensuing dynamics manifests in the form of vibrational features in the photoelectron spectrum.…”