Note: Absolute photoionization cross-section of the vinyl radical

This work measures the absolute photoionization cross-section of the vinyl radical (σ vinyl(E)) between 8.1 and 11.0 eV. Two different methods were used to obtain absolute cross-section measurements: 193 nm photodissociation of methyl vinyl ketone (MVK) and 248 nm photodissociation of vinyl iodide (VI). The values of the photoionization cross-section for the vinyl radical using MVK, σ vinyl(10.224 eV) = (6.1 ± 1.4) Mb and σ vinyl(10.424 eV) = (8.3 ± 1.9) Mb, and using VI, σ vinyl(10.013 eV) = (4.7 ± 1.1) Mb, σ vinyl(10.513 eV) = (9.0 ± 2.1) Mb, and σ vinyl(10.813 eV) = (12.1 ± 2.9) Mb, define a photoionization cross-section that is ∼1.7 times smaller than a previous determination of this value.