On the ionization energies of C4H3 isomers

We have investigated the ionization potentials of resonantly stabilized C4H3 radicals utilizing laser ablation of graphite in combination with seeding the ablated species in neat methylacetylene gas, which also reacted as a reagent. Photoionization efficiency (PIE) curves were recorded of photoionized isomers at the Advanced Light Source. The PIE curve suggests the formation of four C4H3 radicals: two acyclic structures i-C4H3 [1] and E/Z-n-C4H3 [2E/2Z] and two cyclic isomers 3 and 4. This study provides a novel interpretation of previous data on C4H3 radicals in hydrocarbon flames.