Photodissociation of Methylacetylene at 193 nm

Article abstract of DOI:10.1021/j100187a031

The photolysis of methylacetylene (MA) at 193 nm was studied using Fourier transform infrared spectroscopy for product analysis.Main primary processes are CH3C2H + h*ν -> CH3C2 + H and CH3C2H + h*ν -> CH2 + C2H2 with a quantum yield of 0.7 +/- 0.1 and 0.11 +/- 0.01, respectively.Cl2 was used as H atom scavenger.The CD3C2H photolysis was used to confirm that acetylene-d₁ formed is a primary product and is independent of reactant pressures.The H atom addition to the center carbon atom of CD3C2H produces CD3 + C2H2 with a yield of 0.10 +/- 0.01; C2H2 is reduced to almost zero above 5 Torr of MA.The remaining H atom addition to the end carbon would produce allene and propylene.The photolysis of CD3C2H and Cl2 mixtures produces only HCl and DCl is not found, indicating that H atoms are dissociated immediately from the triple-bonded carbon, although the C-D bond in CD3C2H is much weaker.